Grade 8 Integrated Science — Term 1 Notes

<h1 class="notes-h1">GRADE 8 INTEGRATED SCIENCE — TERM 1 NOTES</h1>
<h2 class="notes-h2">CBC Junior Secondary | Kenya Institute of Curriculum Development (KICD) Aligned</h2>
<h3 class="notes-h3">CBCEduKenya.com | cbcedukenya@gmail.com | WhatsApp: 0711 344 702</h3>
<hr class="section-divider">
<p><strong>Grade:</strong> 8 | <strong>Learning Area:</strong> Integrated Science | <strong>Term:</strong> 1</p>
<p><strong>Strands Covered:</strong> Scientific Investigation · Living Things and Their Environment · Matter · Energy · Earth and Beyond</p>
<hr class="section-divider">
<h2 class="notes-h2">STRAND 1: SCIENTIFIC INVESTIGATION</h2>
<h3 class="notes-h3">Sub-Strand 1.1: Scientific Inquiry and Problem Solving</h3>
<p><strong>Specific Learning Outcomes:</strong></p>
<p>By the end of this sub-strand, the learner should be able to:</p>
<ul class="notes-list">
<li>Identify a problem or question for scientific investigation</li>
<li>Formulate a testable hypothesis based on observations</li>
<li>Design a fair experiment to test a hypothesis</li>
<li>Collect, record, and analyse data accurately</li>
<li>Draw valid conclusions supported by evidence</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">What Is Scientific Inquiry?</h4>
<p>Scientific inquiry is a systematic process used to investigate questions and solve problems using evidence. It follows a logical sequence of steps.</p>
<p><strong>The Scientific Method — Steps:</strong></p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Step</th><th>What You Do</th><th>Example</th></tr>
</thead><tbody>
<tr><td>1. Observation</td><td>Notice something interesting</td><td>"Hot water in a cup cools down over time"</td></tr>
<tr><td>2. Question</td><td>Ask a testable question</td><td>"Does the colour of a cup affect how fast water cools?"</td></tr>
<tr><td>3. Hypothesis</td><td>Predict the answer (If…then…because)</td><td>"If the cup is darker, then water will cool faster, because dark surfaces radiate heat more."</td></tr>
<tr><td>4. Experiment</td><td>Test the hypothesis fairly</td><td>Use identical cups of different colours, same amount of water, same room</td></tr>
<tr><td>5. Data Collection</td><td>Measure and record results</td><td>Temperature every 5 minutes for 30 minutes</td></tr>
<tr><td>6. Analysis</td><td>Look for patterns in the data</td><td>Draw a graph; compare cooling rates</td></tr>
<tr><td>7. Conclusion</td><td>State whether the hypothesis was supported</td><td>"The black cup cooled fastest, supporting the hypothesis"</td></tr>
<tr><td>8. Communication</td><td>Share findings</td><td>Write a report; present to the class</td></tr>
</tbody></table></div>
<hr class="section-divider">
<h4 class="notes-h4">Variables in an Experiment</h4>
<p>A <strong>fair test</strong> changes only ONE variable at a time.</p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Variable Type</th><th>Definition</th><th>Example</th></tr>
</thead><tbody>
<tr><td><strong>Independent variable</strong></td><td>The one you change deliberately</td><td>Cup colour (black, white, silver)</td></tr>
<tr><td><strong>Dependent variable</strong></td><td>What you measure as a result</td><td>Temperature of water</td></tr>
<tr><td><strong>Controlled variables</strong></td><td>Everything kept the same</td><td>Amount of water, starting temperature, room temperature, timing</td></tr>
</tbody></table></div>
<p><strong>Key rule:</strong> Change only the independent variable. Control everything else.</p>
<hr class="section-divider">
<h4 class="notes-h4">Writing a Hypothesis</h4>
<p>A good hypothesis must be:</p>
<ul class="notes-list">
<li><strong>Testable</strong> — you can design an experiment to test it</li>
<li><strong>Specific</strong> — clearly states what will change and what will be measured</li>
<li><strong>Justified</strong> — gives a reason based on prior knowledge</li>
</ul>
<p><strong>Format:</strong> <em>If [independent variable], then [dependent variable], because [reasoning].</em></p>
<p><strong>Examples:</strong></p>
<ul class="notes-list">
<li>"If plants are given more sunlight, then they will grow taller, because photosynthesis requires light energy."</li>
<li>"If the surface area of a solid is increased, then it will dissolve faster, because more particles are exposed to water."</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Recording and Presenting Data</h4>
<p><strong>Tables:</strong></p>
<ul class="notes-list">
<li>Always include a heading</li>
<li>First column = independent variable; second column = dependent variable</li>
<li>Include units in column headings</li>
</ul>
<p><strong>Graphs:</strong></p>
<ul class="notes-list">
<li><strong>Line graph:</strong> Shows change over time (e.g., temperature vs time)</li>
<li><strong>Bar graph:</strong> Compares separate groups (e.g., crop yield in different soils)</li>
<li><strong>Pie chart:</strong> Shows proportions of a whole</li>
</ul>
<p><strong>Graph rules:</strong></p>
<ul class="notes-list">
<li>Label both axes with quantity AND unit: e.g., <em>Temperature (°C)</em></li>
<li>Give the graph a title</li>
<li>Use an appropriate scale</li>
<li>Join line graph points with a smooth curve or straight lines</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Drawing Conclusions</h4>
<p>A conclusion must:</p>
<ol class="notes-list">
<li>State whether the hypothesis was supported or not supported</li>
<li>Summarise what the data shows</li>
<li>Explain using scientific knowledge</li>
<li>Acknowledge any sources of error</li>
</ol>
<p><strong>Conclusion format:</strong></p>
<p><em>"The results show that [summary of data]. This [supports / does not support] the hypothesis that [restate hypothesis], because [scientific explanation]. Sources of error may include [list any]."</em></p>
<hr class="section-divider">
<h3 class="notes-h3">Sub-Strand 1.2: Laboratory Safety and Equipment</h3>
<p><strong>Key safety rules:</strong></p>
<ul class="notes-list">
<li>Always wear protective gear: goggles, lab coat, closed shoes</li>
<li>Never taste or smell chemicals directly — waft gently</li>
<li>Know the location of fire extinguisher, first aid kit, and emergency exit</li>
<li>Tie back long hair; avoid loose clothing near flames</li>
<li>Handle glassware carefully; report breakages immediately</li>
<li>Wash hands thoroughly after experiments</li>
</ul>
<p><strong>Common laboratory equipment:</strong></p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Equipment</th><th>Use</th></tr>
</thead><tbody>
<tr><td>Beaker</td><td>Holding and heating liquids</td></tr>
<tr><td>Conical flask</td><td>Mixing; holding liquids during titration</td></tr>
<tr><td>Measuring cylinder</td><td>Measuring volume of liquids accurately</td></tr>
<tr><td>Bunsen burner</td><td>Heating substances</td></tr>
<tr><td>Tripod stand + gauze</td><td>Supporting containers over Bunsen burner</td></tr>
<tr><td>Thermometer</td><td>Measuring temperature</td></tr>
<tr><td>Forceps / tongs</td><td>Handling hot objects</td></tr>
<tr><td>Test tube + holder</td><td>Small-scale heating of substances</td></tr>
<tr><td>Spatula</td><td>Transferring solid chemicals</td></tr>
<tr><td>Dropper / pipette</td><td>Transferring small volumes of liquid</td></tr>
<tr><td>Balance / scale</td><td>Measuring mass</td></tr>
<tr><td>Stop clock</td><td>Measuring time</td></tr>
</tbody></table></div>
<p><strong>Bunsen burner flames:</strong></p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Flame Type</th><th>Appearance</th><th>Use</th></tr>
</thead><tbody>
<tr><td>Safety flame</td><td>Yellow/orange</td><td>Not in use (standby)</td></tr>
<tr><td>Roaring flame</td><td>Blue (fully open)</td><td>Strong, rapid heating</td></tr>
<tr><td>Blue flame</td><td>Small blue</td><td>Gentle heating</td></tr>
</tbody></table></div>
<hr class="section-divider">
<h3 class="notes-h3">Review Questions — Strand 1</h3>
<ol class="notes-list">
<li>State the five steps of the scientific method in the correct order.</li>
<li>A learner wants to find out whether temperature affects the rate at which sugar dissolves. Identify the independent variable, dependent variable, and two controlled variables.</li>
<li>Write a hypothesis for the following question: "Does the amount of water given to a plant affect how tall it grows?"</li>
<li>Explain the difference between a line graph and a bar graph. Give one example of when you would use each.</li>
<li>State three safety rules that must be followed in a science laboratory.</li>
</ol>
<hr class="section-divider">
<h2 class="notes-h2">STRAND 2: LIVING THINGS AND THEIR ENVIRONMENT</h2>
<h3 class="notes-h3">Sub-Strand 2.1: Nutrition in Plants and Animals</h3>
<p><strong>Specific Learning Outcomes:</strong></p>
<p>By the end of this sub-strand, the learner should be able to:</p>
<ul class="notes-list">
<li>Explain the process of photosynthesis and the factors that affect it</li>
<li>Describe the process of respiration in plants and animals</li>
<li>Compare autotrophic and heterotrophic nutrition</li>
<li>Explain the importance of enzymes in digestion</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Autotrophic vs Heterotrophic Nutrition</h4>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Feature</th><th>Autotrophs</th><th>Heterotrophs</th></tr>
</thead><tbody>
<tr><td>Definition</td><td>Make their own food</td><td>Depend on other organisms for food</td></tr>
<tr><td>Examples</td><td>Green plants, algae</td><td>Animals, fungi, most bacteria</td></tr>
<tr><td>Process</td><td>Photosynthesis</td><td>Digestion</td></tr>
<tr><td>Energy source</td><td>Sunlight (mainly)</td><td>Chemical energy from food</td></tr>
</tbody></table></div>
<hr class="section-divider">
<h4 class="notes-h4">Photosynthesis</h4>
<p>Photosynthesis is the process by which green plants use light energy to convert carbon dioxide and water into glucose and oxygen.</p>
<p><strong>Word equation:</strong></p>
<blockquote class="notes-quote"><p>Carbon dioxide + Water → Glucose + Oxygen</p></blockquote>
<blockquote class="notes-quote"><p><em>(using light energy and chlorophyll)</em></p></blockquote>
<p><strong>Chemical equation:</strong></p>
<blockquote class="notes-quote"><p>6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂</p></blockquote>
<p><strong>Conditions needed for photosynthesis:</strong></p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Condition</th><th>Role</th></tr>
</thead><tbody>
<tr><td>Light (sunlight)</td><td>Energy source</td></tr>
<tr><td>Carbon dioxide</td><td>Raw material (enters through stomata)</td></tr>
<tr><td>Water</td><td>Raw material (absorbed through roots)</td></tr>
<tr><td>Chlorophyll</td><td>Absorbs light energy; found in chloroplasts</td></tr>
</tbody></table></div>
<p><strong>Products of photosynthesis:</strong></p>
<ul class="notes-list">
<li><strong>Glucose</strong> — used for energy (respiration), stored as starch, or used to make cellulose and proteins</li>
<li><strong>Oxygen</strong> — released through stomata as a by-product</li>
</ul>
<p><strong>Factors affecting the rate of photosynthesis:</strong></p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Factor</th><th>Effect on rate</th></tr>
</thead><tbody>
<tr><td>Light intensity</td><td>More light → faster rate (up to a maximum)</td></tr>
<tr><td>CO₂ concentration</td><td>More CO₂ → faster rate (up to a maximum)</td></tr>
<tr><td>Temperature</td><td>Warmer → faster rate (until enzymes denature above ~40°C)</td></tr>
<tr><td>Water availability</td><td>Less water → stomata close → rate decreases</td></tr>
<tr><td>Chlorophyll</td><td>More chlorophyll → greater absorption of light</td></tr>
</tbody></table></div>
<p><strong>Leaf adaptations for photosynthesis:</strong></p>
<ul class="notes-list">
<li><strong>Broad and flat</strong> — large surface area to absorb more light</li>
<li><strong>Thin</strong> — short distance for CO₂ and light to penetrate</li>
<li><strong>Many chloroplasts</strong> in palisade mesophyll cells — absorb maximum light</li>
<li><strong>Stomata on lower surface</strong> — allow gas exchange (CO₂ in, O₂ out)</li>
<li><strong>Vascular bundles (veins)</strong> — transport water (xylem) and glucose (phloem)</li>
<li><strong>Transparent epidermis</strong> — allows light to reach mesophyll</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Testing a Leaf for Starch (Iodine Test)</h4>
<p><strong>Purpose:</strong> To show that a plant has carried out photosynthesis and stored starch.</p>
<p><strong>Procedure:</strong></p>
<ol class="notes-list">
<li>Remove a leaf from a plant kept in sunlight for several hours.</li>
<li>Place the leaf in boiling water for 2 minutes to soften it and stop chemical reactions.</li>
<li>Place the leaf in boiling ethanol (using a water bath — NOT directly over a flame) for 5–10 minutes to remove the chlorophyll.</li>
<li>Wash the leaf gently in cold water to rehydrate it.</li>
<li>Spread the leaf flat on a white tile.</li>
<li>Add a few drops of iodine solution.</li>
</ol>
<p><strong>Result:</strong></p>
<ul class="notes-list">
<li>Leaf turns <strong>blue-black</strong> → starch is present → photosynthesis occurred</li>
<li>Leaf stays <strong>brown/yellow</strong> (iodine colour) → no starch → no photosynthesis</li>
</ul>
<p><strong>Variegated leaf experiment:</strong> Tests whether chlorophyll is necessary for photosynthesis. Only the green (chlorophyll-containing) parts turn blue-black; the white parts remain brown.</p>
<hr class="section-divider">
<h4 class="notes-h4">Respiration</h4>
<p>Respiration is the process by which cells break down glucose to release energy for life processes.</p>
<p><strong>Aerobic respiration</strong> (requires oxygen):</p>
<blockquote class="notes-quote"><p>Glucose + Oxygen → Carbon dioxide + Water + Energy</p></blockquote>
<p><strong>Chemical equation:</strong></p>
<blockquote class="notes-quote"><p>C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (ATP)</p></blockquote>
<p><strong>Anaerobic respiration</strong> (without oxygen):</p>
<ul class="notes-list">
<li>In animals/humans: Glucose → Lactic acid + Energy (small amount)</li>
<li>In yeast/plants: Glucose → Ethanol + Carbon dioxide + Energy</li>
</ul>
<p><strong>Comparison:</strong></p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Feature</th><th>Aerobic</th><th>Anaerobic</th></tr>
</thead><tbody>
<tr><td>Oxygen needed</td><td>Yes</td><td>No</td></tr>
<tr><td>Products</td><td>CO₂ + H₂O</td><td>Lactic acid (animals) or Ethanol + CO₂ (yeast)</td></tr>
<tr><td>Energy released</td><td>Large amount</td><td>Small amount</td></tr>
<tr><td>Location in cell</td><td>Mitochondria</td><td>Cytoplasm</td></tr>
</tbody></table></div>
<p><strong>Why respiration is important:</strong></p>
<ul class="notes-list">
<li>Provides energy for movement, growth, and all metabolic processes</li>
<li>Occurs in EVERY living cell, at all times</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Digestion and Enzymes</h4>
<p><strong>Digestion</strong> is the breakdown of large, insoluble food molecules into small, soluble molecules that can be absorbed into the bloodstream.</p>
<p><strong>Two types:</strong></p>
<ul class="notes-list">
<li><strong>Mechanical digestion</strong> — physical breakdown (chewing, churning in stomach)</li>
<li><strong>Chemical digestion</strong> — breakdown using enzymes</li>
</ul>
<p><strong>Enzymes</strong> are biological catalysts — proteins that speed up chemical reactions without being used up.</p>
<p><strong>Key digestive enzymes:</strong></p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Enzyme</th><th>Where produced</th><th>Acts on</th><th>Product</th></tr>
</thead><tbody>
<tr><td>Amylase</td><td>Salivary glands, pancreas</td><td>Starch</td><td>Maltose</td></tr>
<tr><td>Protease (pepsin, trypsin)</td><td>Stomach, pancreas</td><td>Proteins</td><td>Amino acids</td></tr>
<tr><td>Lipase</td><td>Pancreas</td><td>Fats (lipids)</td><td>Fatty acids + glycerol</td></tr>
</tbody></table></div>
<p><strong>Digestive system — journey of food:</strong></p>
<ol class="notes-list">
<li><strong>Mouth</strong> — teeth chew food; salivary amylase begins starch digestion</li>
<li><strong>Oesophagus</strong> — muscular tube; peristalsis moves food to stomach</li>
<li><strong>Stomach</strong> — muscular sac; pepsin digests protein; HCl kills bacteria and activates pepsin; food becomes chyme</li>
<li><strong>Small intestine (duodenum + ileum)</strong> — main site of digestion and absorption; bile (from liver, stored in gall bladder) emulsifies fats; pancreatic enzymes complete digestion; villi absorb nutrients</li>
<li><strong>Large intestine (colon)</strong> — absorbs water; bacteria digest remaining fibre</li>
<li><strong>Rectum/Anus</strong> — undigested matter stored and egested as faeces</li>
</ol>
<p><strong>Villi adaptations for absorption:</strong></p>
<ul class="notes-list">
<li><strong>Finger-like projections</strong> — greatly increase surface area</li>
<li><strong>Microvilli (brush border)</strong> — further increase surface area</li>
<li><strong>Rich blood supply (capillaries)</strong> — carry absorbed nutrients to liver via hepatic portal vein</li>
<li><strong>Lacteals</strong> — absorb fatty acids and glycerol</li>
<li><strong>Thin wall (one cell thick)</strong> — short diffusion distance</li>
</ul>
<hr class="section-divider">
<h3 class="notes-h3">Sub-Strand 2.2: Interdependence of Living Things</h3>
<p><strong>Specific Learning Outcomes:</strong></p>
<p>By the end of this sub-strand, the learner should be able to:</p>
<ul class="notes-list">
<li>Construct and interpret food chains and food webs</li>
<li>Explain the flow of energy through an ecosystem</li>
<li>Describe the effects of human activities on ecosystems</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Food Chains and Food Webs</h4>
<p><strong>Food chain:</strong> Shows the transfer of energy from one organism to another through feeding.</p>
<p><strong>Format:</strong> Producer → Primary consumer → Secondary consumer → Tertiary consumer</p>
<p><strong>Example (Kenyan savanna):</strong></p>
<blockquote class="notes-quote"><p>Grass → Zebra → Lion</p></blockquote>
<p><strong>Example (freshwater pond):</strong></p>
<blockquote class="notes-quote"><p>Algae → Water flea → Small fish → Large fish → Heron</p></blockquote>
<p><strong>Key terms:</strong></p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Term</th><th>Definition</th></tr>
</thead><tbody>
<tr><td><strong>Producer</strong></td><td>Makes own food through photosynthesis (green plant)</td></tr>
<tr><td><strong>Consumer</strong></td><td>Organism that eats other organisms</td></tr>
<tr><td><strong>Primary consumer</strong></td><td>Eats producers (herbivore)</td></tr>
<tr><td><strong>Secondary consumer</strong></td><td>Eats primary consumers</td></tr>
<tr><td><strong>Tertiary consumer</strong></td><td>Eats secondary consumers</td></tr>
<tr><td><strong>Decomposer</strong></td><td>Breaks down dead organisms (fungi, bacteria)</td></tr>
<tr><td><strong>Trophic level</strong></td><td>Position in the food chain</td></tr>
</tbody></table></div>
<p><strong>Food web:</strong> Multiple interconnected food chains in an ecosystem. More realistic than a single food chain.</p>
<hr class="section-divider">
<h4 class="notes-h4">Energy Flow Through Ecosystems</h4>
<p>Energy enters ecosystems through photosynthesis (from sunlight).</p>
<p><strong>Energy is LOST at each trophic level</strong> because organisms:</p>
<ul class="notes-list">
<li>Use energy for movement and warmth</li>
<li>Lose energy as heat</li>
<li>Cannot digest all food (some is excreted)</li>
<li>Die without being eaten</li>
</ul>
<p><strong>Only about 10% of energy is transferred</strong> from one trophic level to the next.</p>
<p>This means food chains rarely have more than 5 levels (too little energy at the top).</p>
<p><strong>Pyramid of numbers:</strong> Shows the number of organisms at each trophic level.</p>
<p><strong>Pyramid of biomass:</strong> Shows the mass (amount of living material) at each trophic level. Always a true pyramid shape.</p>
<hr class="section-divider">
<h4 class="notes-h4">Human Impact on Ecosystems</h4>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Human Activity</th><th>Effect on Ecosystem</th></tr>
</thead><tbody>
<tr><td>Deforestation</td><td>Loss of habitat; soil erosion; reduced rainfall; extinction of species</td></tr>
<tr><td>Pollution (water, air, soil)</td><td>Kills organisms; disrupts food chains; bioaccumulation of toxins</td></tr>
<tr><td>Overfishing</td><td>Collapse of fish populations; food web disruption</td></tr>
<tr><td>Introduction of invasive species</td><td>Native species outcompeted; biodiversity reduced</td></tr>
<tr><td>Overgrazing</td><td>Soil erosion; desertification</td></tr>
<tr><td>Burning fossil fuels</td><td>CO₂ increases → global warming → climate change</td></tr>
</tbody></table></div>
<p><strong>Conservation strategies:</strong></p>
<ul class="notes-list">
<li>Game reserves and national parks (Kenya has over 50)</li>
<li>Legal protection of endangered species</li>
<li>Afforestation and reforestation programmes</li>
<li>Sustainable fishing (quotas, size limits)</li>
<li>Organic farming to reduce chemical use</li>
<li>Environmental education</li>
</ul>
<hr class="section-divider">
<h3 class="notes-h3">Review Questions — Strand 2</h3>
<ol class="notes-list">
<li>Write the word equation for photosynthesis. State three factors that can limit the rate of photosynthesis.</li>
<li>Describe the iodine test for starch. What result would you expect if a leaf was kept in the dark for 24 hours before testing? Explain your answer.</li>
<li>Compare aerobic and anaerobic respiration under the headings: oxygen required, products, and energy released.</li>
<li>Name the enzyme that digests starch. Where is it produced, and what does it produce?</li>
<li>Construct a food chain with four organisms from a grassland ecosystem in Kenya. Identify the producer and the secondary consumer.</li>
<li>Explain why only about 10% of energy is transferred from one trophic level to the next.</li>
<li>State two ways in which human activities are negatively affecting ecosystems in Kenya, and suggest one conservation strategy for each.</li>
</ol>
<hr class="section-divider">
<h2 class="notes-h2">STRAND 3: MATTER</h2>
<h3 class="notes-h3">Sub-Strand 3.1: States of Matter and Changes of State</h3>
<p><strong>Specific Learning Outcomes:</strong></p>
<p>By the end of this sub-strand, the learner should be able to:</p>
<ul class="notes-list">
<li>Describe the arrangement and movement of particles in solids, liquids, and gases</li>
<li>Explain changes of state using particle theory</li>
<li>Interpret heating and cooling curves</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Particle Theory of Matter</h4>
<p>All matter is made of tiny particles (atoms or molecules) that:</p>
<ul class="notes-list">
<li>Are always moving</li>
<li>Have spaces between them</li>
<li>Attract each other</li>
<li>Move faster when heated and slower when cooled</li>
</ul>
<p><strong>The three states of matter:</strong></p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Property</th><th>Solid</th><th>Liquid</th><th>Gas</th></tr>
</thead><tbody>
<tr><td>Particle arrangement</td><td>Regular, close-packed</td><td>Random, close together</td><td>Random, far apart</td></tr>
<tr><td>Particle movement</td><td>Vibrate in fixed positions</td><td>Move freely, randomly</td><td>Move rapidly in all directions</td></tr>
<tr><td>Volume</td><td>Fixed</td><td>Fixed</td><td>No fixed volume</td></tr>
<tr><td>Shape</td><td>Fixed</td><td>Takes shape of container</td><td>Fills container</td></tr>
<tr><td>Compressibility</td><td>Cannot be compressed</td><td>Barely compressible</td><td>Highly compressible</td></tr>
<tr><td>Density</td><td>High</td><td>Medium</td><td>Very low</td></tr>
</tbody></table></div>
<hr class="section-divider">
<h4 class="notes-h4">Changes of State</h4>
<p><strong>Diagram of changes of state:</strong></p>
<pre class="code-block"><code>
MELTING (solid → liquid) BOILING/EVAPORATION (liquid → gas)
SOLID ──────────────────────── LIQUID ──────────────────────────────── GAS
FREEZING (liquid → solid) CONDENSATION (gas → liquid)

SOLID ────────────────────────────────────────────────────────────────── GAS
SUBLIMATION (solid → gas directly)
DEPOSITION (gas → solid directly) ← reverse
</code></pre>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Change of State</th><th>Name</th><th>Energy change</th></tr>
</thead><tbody>
<tr><td>Solid → Liquid</td><td>Melting</td><td>Energy absorbed</td></tr>
<tr><td>Liquid → Solid</td><td>Freezing / Solidification</td><td>Energy released</td></tr>
<tr><td>Liquid → Gas</td><td>Evaporation / Boiling</td><td>Energy absorbed</td></tr>
<tr><td>Gas → Liquid</td><td>Condensation</td><td>Energy released</td></tr>
<tr><td>Solid → Gas (direct)</td><td>Sublimation</td><td>Energy absorbed</td></tr>
<tr><td>Gas → Solid (direct)</td><td>Deposition</td><td>Energy released</td></tr>
</tbody></table></div>
<p><strong>Evaporation vs Boiling:</strong></p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Feature</th><th>Evaporation</th><th>Boiling</th></tr>
</thead><tbody>
<tr><td>Where it occurs</td><td>Surface only</td><td>Throughout the liquid</td></tr>
<tr><td>Temperature</td><td>Any temperature</td><td>At the boiling point</td></tr>
<tr><td>Rate</td><td>Slow</td><td>Fast</td></tr>
<tr><td>Bubbles visible</td><td>No</td><td>Yes</td></tr>
</tbody></table></div>
<hr class="section-divider">
<h4 class="notes-h4">Heating and Cooling Curves</h4>
<p><strong>Heating curve</strong> — shows temperature change as a substance is heated at a constant rate:</p>
<pre class="code-block"><code>
Temperature
| ___________ (gas phase)
| ___________/ (boiling point plateau)
| /
| ___________/ (melting point plateau)
| /
|/ (solid heating)
|________________________
Time
</code></pre>
<p><strong>Key features:</strong></p>
<ul class="notes-list">
<li><strong>Sloped sections</strong> — temperature rises; single state present; energy goes into increasing kinetic energy</li>
<li><strong>Flat (plateau) sections</strong> — temperature stays constant; state is CHANGING; energy goes into breaking intermolecular bonds, not raising temperature</li>
</ul>
<p><strong>Melting point and boiling point are characteristic of each pure substance.</strong> Mixed or impure substances have lower melting points and higher boiling points.</p>
<hr class="section-divider">
<h3 class="notes-h3">Sub-Strand 3.2: Elements, Compounds, and Mixtures</h3>
<p><strong>Specific Learning Outcomes:</strong></p>
<p>By the end of this sub-strand, the learner should be able to:</p>
<ul class="notes-list">
<li>Distinguish between elements, compounds, and mixtures</li>
<li>Describe methods of separating mixtures</li>
<li>Explain the difference between physical and chemical changes</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Elements, Compounds, and Mixtures</h4>
<p><strong>Element:</strong> A pure substance made of only one type of atom. Cannot be broken down by chemical means.</p>
<ul class="notes-list">
<li>Examples: Oxygen (O), Hydrogen (H), Iron (Fe), Copper (Cu), Carbon (C), Gold (Au)</li>
<li>Total of 118 elements in the Periodic Table</li>
</ul>
<p><strong>Compound:</strong> A pure substance formed when two or more elements are chemically combined in fixed proportions.</p>
<ul class="notes-list">
<li>Properties are DIFFERENT from those of the constituent elements</li>
<li>Can only be separated by chemical means</li>
<li>Examples: Water (H₂O), Salt (NaCl), Carbon dioxide (CO₂), Glucose (C₆H₁₂O₆)</li>
</ul>
<p><strong>Mixture:</strong> Two or more substances combined but NOT chemically bonded.</p>
<ul class="notes-list">
<li>Components keep their own properties</li>
<li>Can be separated by physical means</li>
<li>Composition can vary</li>
<li>Examples: Air, salt water, soil, blood, alloys</li>
</ul>
<p><strong>Comparison:</strong></p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Feature</th><th>Element</th><th>Compound</th><th>Mixture</th></tr>
</thead><tbody>
<tr><td>Composition</td><td>1 type of atom</td><td>2+ elements in fixed ratio</td><td>2+ substances in any ratio</td></tr>
<tr><td>Properties</td><td>Unique to element</td><td>Different from elements</td><td>Components keep own properties</td></tr>
<tr><td>Separation</td><td>Cannot separate chemically</td><td>Chemical methods only</td><td>Physical methods</td></tr>
<tr><td>Pure substance?</td><td>Yes</td><td>Yes</td><td>No</td></tr>
</tbody></table></div>
<hr class="section-divider">
<h4 class="notes-h4">Separation Techniques</h4>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Technique</th><th>Principle</th><th>Used for</th></tr>
</thead><tbody>
<tr><td><strong>Filtration</strong></td><td>Separates insoluble solid from liquid using filter paper</td><td>Sand from water, chalk from water</td></tr>
<tr><td><strong>Evaporation</strong></td><td>Liquid evaporates, leaving dissolved solid</td><td>Salt from salt solution</td></tr>
<tr><td><strong>Distillation</strong></td><td>Liquid boils, condenses, and collects separately</td><td>Pure water from salt water; ethanol from water</td></tr>
<tr><td><strong>Crystallisation</strong></td><td>Dissolved solid forms crystals as solution cools</td><td>Copper sulphate, sugar crystals</td></tr>
<tr><td><strong>Chromatography</strong></td><td>Different substances move at different rates on paper</td><td>Separating inks/dyes; testing food colourings</td></tr>
<tr><td><strong>Magnetic separation</strong></td><td>Magnetic material attracted to magnet</td><td>Iron filings from sand</td></tr>
<tr><td><strong>Decanting</strong></td><td>Carefully pouring liquid away from settled solid</td><td>Muddy water</td></tr>
<tr><td><strong>Centrifugation</strong></td><td>Spinning forces denser material to bottom</td><td>Blood cells from plasma</td></tr>
</tbody></table></div>
<p><strong>Chromatography — Key terms:</strong></p>
<ul class="notes-list">
<li><strong>Solvent</strong> — liquid that moves up the paper and carries pigments</li>
<li><strong>Baseline</strong> — line where sample is placed (must be above solvent level)</li>
<li><strong>Rf value</strong> — Rf = distance moved by spot ÷ distance moved by solvent front</li>
<li>Each substance has a characteristic Rf value for a given solvent</li>
<li>Used to identify unknown substances by comparing Rf values</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Physical vs Chemical Changes</h4>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Feature</th><th>Physical Change</th><th>Chemical Change</th></tr>
</thead><tbody>
<tr><td>New substance formed?</td><td>No</td><td>Yes</td></tr>
<tr><td>Reversible?</td><td>Usually</td><td>Usually not</td></tr>
<tr><td>Examples</td><td>Melting, dissolving, tearing</td><td>Burning, rusting, cooking, decomposition</td></tr>
<tr><td>Energy change</td><td>Small</td><td>Usually significant</td></tr>
<tr><td>Evidence</td><td>Change in shape/state</td><td>Gas produced, precipitate, colour change, heat/light produced</td></tr>
</tbody></table></div>
<p><strong>Signs a chemical change has occurred:</strong></p>
<ul class="notes-list">
<li>Colour change (not just mixing colours)</li>
<li>Gas produced (bubbles, fizzing)</li>
<li>Precipitate formed (solid appears in solution)</li>
<li>Temperature change (gets very hot or very cold)</li>
<li>Light produced</li>
<li>Smell produced</li>
<li>Change is irreversible</li>
</ul>
<hr class="section-divider">
<h3 class="notes-h3">Review Questions — Strand 3</h3>
<ol class="notes-list">
<li>Describe the arrangement and movement of particles in (a) a solid, (b) a gas.</li>
<li>Name the change of state that occurs when: (a) ice melts, (b) steam forms on a mirror, (c) iodine crystals turn directly into purple vapour.</li>
<li>Explain why temperature stays constant at the melting point even though heat is being added continuously.</li>
<li>Distinguish between a compound and a mixture. Give one example of each.</li>
<li>A learner has a mixture of sand, salt, and iron filings. Describe, in steps, how they could separate all three components.</li>
<li>State three signs that indicate a chemical change has taken place.</li>
</ol>
<hr class="section-divider">
<h2 class="notes-h2">STRAND 4: ENERGY</h2>
<h3 class="notes-h3">Sub-Strand 4.1: Forms and Transformations of Energy</h3>
<p><strong>Specific Learning Outcomes:</strong></p>
<p>By the end of this sub-strand, the learner should be able to:</p>
<ul class="notes-list">
<li>Identify and describe different forms of energy</li>
<li>Explain energy transformations in common devices</li>
<li>Apply the principle of conservation of energy</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Forms of Energy</h4>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Form</th><th>Description</th><th>Examples</th></tr>
</thead><tbody>
<tr><td><strong>Kinetic energy</strong></td><td>Energy of moving objects</td><td>Moving car, flowing water, wind</td></tr>
<tr><td><strong>Potential energy</strong></td><td>Stored energy due to position or state</td><td>Book on a shelf (gravitational PE), compressed spring (elastic PE), fuel (chemical PE)</td></tr>
<tr><td><strong>Thermal (heat) energy</strong></td><td>Energy due to temperature; kinetic energy of particles</td><td>Hot soup, steam, warm rock</td></tr>
<tr><td><strong>Light (radiant) energy</strong></td><td>Electromagnetic radiation visible to the eye</td><td>Sunlight, flame, light bulb</td></tr>
<tr><td><strong>Sound energy</strong></td><td>Vibration of particles</td><td>Music, thunder, voice</td></tr>
<tr><td><strong>Electrical energy</strong></td><td>Movement of electric charges</td><td>Current in a wire</td></tr>
<tr><td><strong>Chemical energy</strong></td><td>Stored in chemical bonds</td><td>Food, fuel, batteries</td></tr>
<tr><td><strong>Nuclear energy</strong></td><td>Stored in nucleus of atoms</td><td>Sun, nuclear power stations</td></tr>
<tr><td><strong>Magnetic energy</strong></td><td>Energy in magnetic fields</td><td>MRI machines, electric motors</td></tr>
</tbody></table></div>
<hr class="section-divider">
<h4 class="notes-h4">Principle of Conservation of Energy</h4>
<p><strong>Energy cannot be created or destroyed. It can only be transformed from one form to another.</strong></p>
<p>The total amount of energy in a closed system remains constant.</p>
<p><strong>Energy transformation examples:</strong></p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Device</th><th>Input energy</th><th>Output energy</th></tr>
</thead><tbody>
<tr><td>Light bulb</td><td>Electrical</td><td>Light + Heat</td></tr>
<tr><td>Solar panel</td><td>Light (solar)</td><td>Electrical</td></tr>
<tr><td>Torch</td><td>Chemical (battery)</td><td>Light + Heat</td></tr>
<tr><td>Microphone</td><td>Sound</td><td>Electrical</td></tr>
<tr><td>Loudspeaker</td><td>Electrical</td><td>Sound</td></tr>
<tr><td>Car engine</td><td>Chemical (fuel)</td><td>Kinetic + Heat + Sound</td></tr>
<tr><td>Kettle</td><td>Electrical</td><td>Thermal (heat)</td></tr>
<tr><td>Generator</td><td>Kinetic (mechanical)</td><td>Electrical</td></tr>
<tr><td>Plant (photosynthesis)</td><td>Light</td><td>Chemical</td></tr>
</tbody></table></div>
<p><strong>Energy efficiency:</strong></p>
<ul class="notes-list">
<li>In most transformations, some energy is "lost" as heat</li>
<li><strong>Efficiency = (useful energy output ÷ total energy input) × 100%</strong></li>
<li>No device is 100% efficient</li>
</ul>
<p><strong>Example:</strong> A light bulb uses 100 J of electrical energy and produces 15 J of light. Efficiency = 15 ÷ 100 × 100% = 15%</p>
<hr class="section-divider">
<h3 class="notes-h3">Sub-Strand 4.2: Heat Transfer</h3>
<p><strong>Specific Learning Outcomes:</strong></p>
<p>By the end of this sub-strand, the learner should be able to:</p>
<ul class="notes-list">
<li>Describe the three methods of heat transfer</li>
<li>Explain everyday applications of heat transfer</li>
<li>Compare good and poor conductors of heat</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Methods of Heat Transfer</h4>
<p><strong>1. Conduction — transfer of heat through a material without the material moving</strong></p>
<ul class="notes-list">
<li>Occurs mainly in <strong>solids</strong></li>
<li>Particles vibrate and pass energy to neighbouring particles</li>
<li><strong>Good conductors:</strong> metals (copper, aluminium, iron) — used in cooking pans, radiators</li>
<li><strong>Poor conductors (insulators):</strong> wood, plastic, glass, air — used in handles, building insulation, clothing</li>
<li><strong>Experiment:</strong> Touch a metal spoon and a wooden spoon in a warm room — the metal feels colder because it conducts heat away from your hand faster</li>
</ul>
<p><strong>2. Convection — transfer of heat by movement of a fluid (liquid or gas)</strong></p>
<ul class="notes-list">
<li>Occurs in <strong>liquids and gases</strong></li>
<li>Warm fluid is less dense → rises; cool fluid is denser → sinks → creates a <strong>convection current</strong></li>
<li><strong>Examples:</strong> Hot water in a kettle circulates; wind patterns (sea breeze); room heaters placed at floor level</li>
</ul>
<p><strong>Sea breeze (daytime):</strong></p>
<ul class="notes-list">
<li>Land heats faster than sea → air over land warms and rises → cool air from sea moves in to replace it → sea breeze blows from sea to land</li>
</ul>
<p><strong>Land breeze (night-time):</strong></p>
<ul class="notes-list">
<li>Land cools faster than sea → air over sea is warmer and rises → cool air from land moves out to sea</li>
</ul>
<p><strong>3. Radiation — transfer of heat by electromagnetic waves (infrared radiation)</strong></p>
<ul class="notes-list">
<li>Does <strong>not</strong> require a medium (can travel through vacuum)</li>
<li>All objects emit radiation; hotter objects emit more</li>
<li><strong>Dark, matt surfaces</strong> are better absorbers and emitters of radiation</li>
<li><strong>Shiny, light surfaces</strong> are better reflectors and poor absorbers</li>
<li><strong>Examples:</strong> Sun's energy reaching Earth; feeling warmth from a fire without touching it; solar cookers; vacuum flask</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Comparison of Heat Transfer Methods</h4>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Feature</th><th>Conduction</th><th>Convection</th><th>Radiation</th></tr>
</thead><tbody>
<tr><td>Medium needed</td><td>Solid particles</td><td>Fluid (liquid/gas)</td><td>None</td></tr>
<tr><td>Particle movement</td><td>Vibrate — do not flow</td><td>Fluid flows</td><td>No particles needed</td></tr>
<tr><td>Common in</td><td>Solids</td><td>Liquids and gases</td><td>All materials; vacuum</td></tr>
<tr><td>Speed</td><td>Slow (in poor conductors)</td><td>Moderate</td><td>Fast (speed of light)</td></tr>
</tbody></table></div>
<hr class="section-divider">
<h4 class="notes-h4">Applications — Keeping Things Hot or Cold</h4>
<p><strong>Vacuum flask (Thermos flask):</strong></p>
<ul class="notes-list">
<li>Double glass walls with vacuum between → no conduction or convection through vacuum</li>
<li>Silvered walls → reflect radiation back</li>
<li>Glass/plastic stopper → reduces conduction through top</li>
<li>Combines ALL THREE methods of reducing heat loss</li>
</ul>
<p><strong>Building insulation:</strong></p>
<ul class="notes-list">
<li>Cavity walls filled with foam → trapped air is a poor conductor</li>
<li>Loft insulation (fibreglass) → traps air</li>
<li>Double glazing → air gap between panes reduces conduction</li>
</ul>
<hr class="section-divider">
<h3 class="notes-h3">Sub-Strand 4.3: Light</h3>
<p><strong>Specific Learning Outcomes:</strong></p>
<p>By the end of this sub-strand, the learner should be able to:</p>
<ul class="notes-list">
<li>Describe the properties of light</li>
<li>Explain reflection and refraction</li>
<li>Construct ray diagrams for mirrors and lenses</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Properties of Light</h4>
<ul class="notes-list">
<li>Light travels in straight lines (<strong>rectilinear propagation</strong>) → evidence: shadows, eclipses</li>
<li>Light travels at approximately <strong>3 × 10⁸ m/s</strong> in a vacuum</li>
<li>Light is a transverse electromagnetic wave</li>
<li>Light does not need a medium to travel</li>
</ul>
<p><strong>Shadows and Eclipses:</strong></p>
<ul class="notes-list">
<li><strong>Umbra</strong> — completely dark central shadow (total eclipse)</li>
<li><strong>Penumbra</strong> — partially dark outer shadow (partial eclipse)</li>
<li><strong>Solar eclipse</strong> — Moon blocks sunlight from reaching Earth (Moon between Earth and Sun)</li>
<li><strong>Lunar eclipse</strong> — Earth blocks sunlight from reaching Moon (Earth between Sun and Moon)</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Reflection</h4>
<p><strong>Law of Reflection:</strong></p>
<blockquote class="notes-quote"><p><em>The angle of incidence (i) equals the angle of reflection (r)</em></p></blockquote>
<blockquote class="notes-quote"><p><em>(Both angles measured from the normal)</em></p></blockquote>
<p><strong>Key terms:</strong></p>
<ul class="notes-list">
<li><strong>Normal</strong> — an imaginary line perpendicular to the mirror surface at the point of incidence</li>
<li><strong>Angle of incidence</strong> — angle between incident ray and normal</li>
<li><strong>Angle of reflection</strong> — angle between reflected ray and normal</li>
</ul>
<p><strong>Image in a plane (flat) mirror:</strong></p>
<ul class="notes-list">
<li>Same size as object</li>
<li>Same distance behind mirror as object is in front</li>
<li>Laterally inverted (left-right reversed)</li>
<li>Virtual (cannot be projected onto a screen)</li>
<li>Upright (same orientation)</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Refraction</h4>
<p><strong>Refraction</strong> occurs when light passes from one medium to another and changes speed, causing a change in direction (unless it hits perpendicular to the boundary).</p>
<p><strong>Key observations:</strong></p>
<ul class="notes-list">
<li>Light bends <strong>towards the normal</strong> when entering a denser medium (e.g., air to glass)</li>
<li>Light bends <strong>away from the normal</strong> when entering a less dense medium (e.g., glass to air)</li>
<li>Frequency does NOT change when light refracts</li>
<li>Speed and wavelength DO change</li>
</ul>
<p><strong>Refractive index (n):</strong> n = speed of light in vacuum ÷ speed of light in medium</p>
<p><strong>Applications of refraction:</strong></p>
<ul class="notes-list">
<li>Apparent depth of water (pool looks shallower than it is)</li>
<li>Lens action in the eye and in glasses</li>
<li>Mirages in hot desert conditions</li>
<li>Pencil appearing bent when placed in water</li>
</ul>
<hr class="section-divider">
<h3 class="notes-h3">Review Questions — Strand 4</h3>
<ol class="notes-list">
<li>Name four forms of energy and give one example of each.</li>
<li>A car converts chemical energy in petrol into kinetic energy. State two other forms of energy produced and explain why this means the car is not 100% efficient.</li>
<li>A torch converts 50 J of chemical energy (battery) into 5 J of light energy. Calculate the efficiency of the torch.</li>
<li>Explain the difference between conduction and convection. State in which state of matter each mainly occurs.</li>
<li>Why are the inner walls of a vacuum flask silvered?</li>
<li>A ray of light hits a plane mirror at an angle of incidence of 35°. What is the angle of reflection? State the law you used.</li>
<li>Explain what happens to a ray of light when it passes from air into glass. Draw a labelled ray diagram to support your answer.</li>
</ol>
<hr class="section-divider">
<h2 class="notes-h2">STRAND 5: EARTH AND BEYOND</h2>
<h3 class="notes-h3">Sub-Strand 5.1: The Atmosphere and Weather</h3>
<p><strong>Specific Learning Outcomes:</strong></p>
<p>By the end of this sub-strand, the learner should be able to:</p>
<ul class="notes-list">
<li>Describe the composition and layers of the atmosphere</li>
<li>Explain weather patterns and their causes</li>
<li>Use weather instruments to measure and record weather data</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Composition of the Atmosphere</h4>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Gas</th><th>Approximate % by volume</th></tr>
</thead><tbody>
<tr><td>Nitrogen (N₂)</td><td>~78%</td></tr>
<tr><td>Oxygen (O₂)</td><td>~21%</td></tr>
<tr><td>Argon (Ar)</td><td>~1%</td></tr>
<tr><td>Carbon dioxide (CO₂)</td><td>~0.04%</td></tr>
<tr><td>Water vapour</td><td>Variable (0–4%)</td></tr>
<tr><td>Other trace gases</td><td>< 0.01%</td></tr>
</tbody></table></div>
<p><strong>Layers of the atmosphere (from Earth's surface upward):</strong></p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Layer</th><th>Height</th><th>Key features</th></tr>
</thead><tbody>
<tr><td>Troposphere</td><td>0–12 km</td><td>Weather occurs here; temperature decreases with altitude</td></tr>
<tr><td>Stratosphere</td><td>12–50 km</td><td>Contains the ozone layer; temperature increases with altitude</td></tr>
<tr><td>Mesosphere</td><td>50–85 km</td><td>Meteors burn up here; coldest layer</td></tr>
<tr><td>Thermosphere</td><td>85–600 km</td><td>Very hot; auroras occur; ISS orbits here</td></tr>
<tr><td>Exosphere</td><td>600 km+</td><td>Merges into outer space</td></tr>
</tbody></table></div>
<p><strong>Ozone layer (stratosphere):</strong></p>
<ul class="notes-list">
<li>Absorbs most of the Sun's harmful ultraviolet (UV) radiation</li>
<li>Protects living things from UV-induced mutations, skin cancer, and cataracts</li>
<li>Damaged by CFCs (chlorofluorocarbons) from old refrigerants and aerosols</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Weather Instruments</h4>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Instrument</th><th>Measures</th><th>Unit</th></tr>
</thead><tbody>
<tr><td>Thermometer</td><td>Temperature</td><td>°C</td></tr>
<tr><td>Rain gauge</td><td>Rainfall / precipitation</td><td>mm</td></tr>
<tr><td>Wind vane (weather vane)</td><td>Wind direction</td><td>Compass direction (N, NE, S, etc.)</td></tr>
<tr><td>Anemometer</td><td>Wind speed</td><td>km/h or knots</td></tr>
<tr><td>Barometer</td><td>Air pressure</td><td>millibars (mb) / hPa</td></tr>
<tr><td>Hygrometer</td><td>Humidity (moisture in air)</td><td>% relative humidity</td></tr>
</tbody></table></div>
<p><strong>Reading a rain gauge:</strong></p>
<ul class="notes-list">
<li>Measures amount of rainfall collected over 24 hours</li>
<li>Read at the same time each day</li>
<li>Units: millimetres (mm) — represents depth of water if it stayed on ground</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Cloud Types and Weather Prediction</h4>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Cloud Type</th><th>Description</th><th>Associated Weather</th></tr>
</thead><tbody>
<tr><td>Cumulus</td><td>Fluffy, white, heaped</td><td>Fair weather (unless very tall)</td></tr>
<tr><td>Cumulonimbus</td><td>Tall, dark, towering</td><td>Thunderstorms, heavy rain</td></tr>
<tr><td>Stratus</td><td>Layer/flat, grey, low</td><td>Drizzle, overcast</td></tr>
<tr><td>Cirrus</td><td>Wispy, high altitude, white</td><td>Fair weather changing</td></tr>
<tr><td>Nimbostratus</td><td>Dark, layered, low</td><td>Steady rain</td></tr>
</tbody></table></div>
<p><strong>Air pressure and weather:</strong></p>
<ul class="notes-list">
<li><strong>High pressure (anticyclone)</strong> → dry, sunny, settled weather</li>
<li><strong>Low pressure (depression/cyclone)</strong> → wet, cloudy, windy weather</li>
</ul>
<hr class="section-divider">
<h3 class="notes-h3">Sub-Strand 5.2: The Solar System and Space Exploration</h3>
<p><strong>Specific Learning Outcomes:</strong></p>
<p>By the end of this sub-strand, the learner should be able to:</p>
<ul class="notes-list">
<li>Describe the structure of the Solar System</li>
<li>Explain the motion of Earth and Moon and their effects</li>
<li>Describe the contributions of space exploration to human life</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">The Solar System</h4>
<p>The Solar System consists of the Sun and all celestial objects gravitationally bound to it.</p>
<p><strong>The eight planets (in order from Sun):</strong></p>
<blockquote class="notes-quote"><p><strong>M</strong>y <strong>V</strong>ery <strong>E</strong>xcited <strong>M</strong>other <strong>J</strong>ust <strong>S</strong>erved <strong>U</strong>s <strong>N</strong>achos</p></blockquote>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Planet</th><th>Key features</th></tr>
</thead><tbody>
<tr><td>Mercury</td><td>Smallest; closest to Sun; no atmosphere; extreme temperature variation</td></tr>
<tr><td>Venus</td><td>Hottest (greenhouse effect); similar size to Earth; rotates backwards</td></tr>
<tr><td>Earth</td><td>Only known planet with life; liquid water; oxygen atmosphere</td></tr>
<tr><td>Mars</td><td>Red planet; largest volcano (Olympus Mons); thin CO₂ atmosphere; 2 moons</td></tr>
<tr><td>Jupiter</td><td>Largest planet; Great Red Spot (storm); 95 known moons; gas giant</td></tr>
<tr><td>Saturn</td><td>Famous rings (ice and rock); least dense planet; gas giant</td></tr>
<tr><td>Uranus</td><td>Rotates on its side; ice giant; faint rings</td></tr>
<tr><td>Neptune</td><td>Farthest; strongest winds; ice giant; 1 large moon (Triton)</td></tr>
</tbody></table></div>
<p><strong>Other bodies in the Solar System:</strong></p>
<ul class="notes-list">
<li><strong>Asteroid belt</strong> — between Mars and Jupiter; rocky bodies</li>
<li><strong>Dwarf planets</strong> — Pluto, Eris, Ceres</li>
<li><strong>Comets</strong> — icy bodies; develop tails when near Sun</li>
<li><strong>Moons</strong> — natural satellites orbiting planets</li>
</ul>
<hr class="section-divider">
<h4 class="notes-h4">Earth's Motions and Their Effects</h4>
<p><strong>Rotation (spinning on axis — 24 hours):</strong></p>
<ul class="notes-list">
<li>Causes day and night</li>
<li>Earth rotates from west to east → Sun appears to rise in east, set in west</li>
</ul>
<p><strong>Revolution (orbit around Sun — 365.25 days):</strong></p>
<ul class="notes-list">
<li>Causes the seasons (in regions far from equator)</li>
<li>Earth's axis is tilted at 23.5° → when a hemisphere tilts towards Sun → summer; tilts away → winter</li>
<li><strong>Kenya is near equator</strong> → seasons are rainy and dry (not hot and cold) because tilt effect is small</li>
</ul>
<p><strong>The Moon's orbit around Earth (~29.5 days = one lunar month):</strong></p>
<ul class="notes-list">
<li>Causes the phases of the Moon</li>
<li>Causes tides (gravitational pull of Moon on Earth's oceans)</li>
</ul>
<p><strong>Moon phases:</strong></p>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Phase</th><th>Appearance</th></tr>
</thead><tbody>
<tr><td>New Moon</td><td>Moon not visible</td></tr>
<tr><td>Waxing Crescent</td><td>Thin sliver (right side lit)</td></tr>
<tr><td>First Quarter</td><td>Half Moon (right side lit)</td></tr>
<tr><td>Waxing Gibbous</td><td>More than half lit (right side)</td></tr>
<tr><td>Full Moon</td><td>Entire face lit</td></tr>
<tr><td>Waning Gibbous</td><td>More than half lit (left side)</td></tr>
<tr><td>Last Quarter</td><td>Half Moon (left side lit)</td></tr>
<tr><td>Waning Crescent</td><td>Thin sliver (left side lit)</td></tr>
</tbody></table></div>
<hr class="section-divider">
<h4 class="notes-h4">Space Exploration</h4>
<p><strong>Key milestones:</strong></p>
<ul class="notes-list">
<li>1957 — Sputnik 1 (first satellite in space, USSR)</li>
<li>1961 — Yuri Gagarin (first human in space, USSR)</li>
<li>1969 — Neil Armstrong and Buzz Aldrin (first humans on Moon, Apollo 11, USA)</li>
<li>1990 — Hubble Space Telescope launched</li>
<li>1998–present — International Space Station (ISS)</li>
<li>2021 — James Webb Space Telescope (launched)</li>
</ul>
<p><strong>Benefits of space exploration:</strong></p>
<ul class="notes-list">
<li>Satellite technology → GPS, weather forecasting, telecommunications</li>
<li>Medical advances (e.g., memory foam, water purification systems)</li>
<li>Solar panels and fuel cell technology</li>
<li>Better understanding of Earth's climate</li>
<li>Monitoring of natural disasters (floods, fires, deforestation)</li>
</ul>
<p><strong>Africa and Kenya in space:</strong></p>
<ul class="notes-list">
<li>Kenya launched its first satellite, <strong>Uhuru (Explorer 42)</strong>, in 1970 from the San Marco platform off Malindi — first X-ray astronomy satellite</li>
<li>Kenya Space Agency (KSA) established in 2017</li>
<li>KRONOS-1 and subsequent nanosatellites by Kenyan students</li>
</ul>
<hr class="section-divider">
<h3 class="notes-h3">Review Questions — Strand 5</h3>
<ol class="notes-list">
<li>State the two most abundant gases in the atmosphere and their approximate percentages.</li>
<li>Explain the role of the ozone layer. Name one substance that damages it.</li>
<li>A weather observer records a rapidly falling barometer reading. What type of weather should they expect? Explain your answer.</li>
<li>Name the four inner (terrestrial) planets in order from the Sun.</li>
<li>Explain how Earth's rotation causes day and night.</li>
<li>Kenya does not experience four seasons (spring, summer, autumn, winter) like countries far from the equator. Explain why.</li>
<li>State two benefits that space exploration has brought to everyday life on Earth.</li>
</ol>
<hr class="section-divider">
<h2 class="notes-h2">KEY VOCABULARY — GRADE 8 INTEGRATED SCIENCE TERM 1</h2>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Term</th><th>Definition</th></tr>
</thead><tbody>
<tr><td>Hypothesis</td><td>A testable prediction explaining an observation</td></tr>
<tr><td>Independent variable</td><td>The variable deliberately changed in an experiment</td></tr>
<tr><td>Dependent variable</td><td>The variable measured as a result of the change</td></tr>
<tr><td>Photosynthesis</td><td>Process by which green plants make food using light energy</td></tr>
<tr><td>Respiration</td><td>Process by which cells break down glucose to release energy</td></tr>
<tr><td>Enzyme</td><td>A biological catalyst that speeds up chemical reactions</td></tr>
<tr><td>Consumer</td><td>An organism that feeds on other organisms</td></tr>
<tr><td>Producer</td><td>An organism that makes its own food (plant)</td></tr>
<tr><td>Evaporation</td><td>Change of state from liquid to gas at the surface</td></tr>
<tr><td>Sublimation</td><td>Change of state from solid directly to gas</td></tr>
<tr><td>Refractive index</td><td>Ratio of speed of light in vacuum to speed in a medium</td></tr>
<tr><td>Conduction</td><td>Transfer of heat through a material without the material moving</td></tr>
<tr><td>Convection</td><td>Transfer of heat by movement of a fluid</td></tr>
<tr><td>Radiation</td><td>Transfer of heat by electromagnetic (infrared) waves</td></tr>
<tr><td>Atmosphere</td><td>The layer of gases surrounding Earth</td></tr>
<tr><td>Ozone layer</td><td>Layer in stratosphere that absorbs harmful UV radiation</td></tr>
<tr><td>Refraction</td><td>Bending of light as it passes from one medium to another</td></tr>
<tr><td>Chromatography</td><td>Separation technique based on different rates of movement</td></tr>
<tr><td>Aerobic respiration</td><td>Respiration requiring oxygen; produces CO₂, water, and energy</td></tr>
<tr><td>Trophic level</td><td>Position of an organism in a food chain</td></tr>
</tbody></table></div>
<hr class="section-divider">
<h2 class="notes-h2">SUMMARY TABLE — STRAND OVERVIEW</h2>
<div class="table-wrap"><table class="notes-table">
<thead>
<tr><th>Strand</th><th>Key Topics</th><th>Key Skills</th></tr>
</thead><tbody>
<tr><td>1. Scientific Investigation</td><td>Scientific method, variables, fair tests, data collection, conclusions</td><td>Designing experiments, drawing graphs, writing conclusions</td></tr>
<tr><td>2. Living Things</td><td>Photosynthesis, respiration, digestion, enzymes, food chains, ecosystems</td><td>Identifying variables, interpreting food webs, evaluating human impact</td></tr>
<tr><td>3. Matter</td><td>States of matter, changes of state, elements/compounds/mixtures, separation</td><td>Separating mixtures, heating curves, classifying substances</td></tr>
<tr><td>4. Energy</td><td>Forms of energy, conservation, transformations, heat transfer, light</td><td>Efficiency calculations, ray diagrams, heat transfer applications</td></tr>
<tr><td>5. Earth and Beyond</td><td>Atmosphere, weather, Solar System, Earth's motions</td><td>Reading weather instruments, constructing planet order, explaining seasons</td></tr>
</tbody></table></div>
<hr class="section-divider">
<h2 class="notes-h2">EXAM-STYLE PRACTICE QUESTIONS</h2>
<p><strong>Section A — Multiple Choice</strong></p>
<ol class="notes-list">
<li>Which of the following is the correct word equation for photosynthesis?</li>
</ol>
<p>A. Glucose + Oxygen → Carbon dioxide + Water + Energy</p>
<p>B. Carbon dioxide + Water → Glucose + Oxygen <em>(correct)</em></p>
<p>C. Carbon dioxide + Oxygen → Glucose + Water</p>
<p>D. Water + Glucose → Oxygen + Carbon dioxide</p>
<ol class="notes-list">
<li>A learner separates a mixture of iron filings, salt, and sand. Which technique would correctly remove the iron filings FIRST?</li>
</ol>
<p>A. Filtration</p>
<p>B. Evaporation</p>
<p>C. Magnetic separation <em>(correct)</em></p>
<p>D. Distillation</p>
<ol class="notes-list">
<li>Which layer of the atmosphere contains the ozone layer?</li>
</ol>
<p>A. Troposphere</p>
<p>B. Stratosphere <em>(correct)</em></p>
<p>C. Mesosphere</p>
<p>D. Thermosphere</p>
<p><strong>Section B — Short Answer</strong></p>
<ol class="notes-list">
<li>A student investigates whether the type of soil affects how fast water drains through it. She tests four soil types (clay, sand, loam, silt) using identical columns.</li>
</ol>
<p>(a) State the independent variable. <em>(1 mark)</em></p>
<p>(b) State two controlled variables. <em>(2 marks)</em></p>
<p>(c) Write a suitable hypothesis for this investigation. <em>(2 marks)</em></p>
<ol class="notes-list">
<li>Describe the process of convection in a room heated by a radiator placed near the floor. Include the words: warm air, less dense, rises, cool air, denser, convection current. <em>(4 marks)</em></li>
</ol>
<ol class="notes-list">
<li>Explain why a vacuum flask keeps liquids hot. Refer to all three methods of heat transfer in your answer. <em>(6 marks)</em></li>
</ol>
<p><strong>Section C — Extended Response</strong></p>
<ol class="notes-list">
<li>(a) Describe the structure and function of villi in the small intestine. Explain three adaptations that make them efficient at absorbing nutrients. <em>(6 marks)</em></li>
</ol>
<p>(b) Compare aerobic and anaerobic respiration in a table with at least four rows. <em>(4 marks)</em></p>
<p>(c) A marathon runner's muscles begin to ache towards the end of a race. Using your knowledge of respiration, explain why this happens. <em>(2 marks)</em></p>
<hr class="section-divider">
<h2 class="notes-h2">MARKING SCHEME — SELECTED QUESTIONS</h2>
<p><strong>Q4(a):</strong> Type of soil [1]</p>
<p><strong>Q4(b):</strong> Any two from: volume/amount of water used; time allowed for draining; temperature; size/height of soil column; depth of soil [2]</p>
<p><strong>Q4(c):</strong> Format: If [soil type], then [drainage rate], because [reason]; must be testable; must state a clear relationship [2]</p>
<p><strong>Q5 (4 marks):</strong></p>
<ul class="notes-list">
<li>Radiator heats air nearby → warm air is less dense than cool air [1]</li>
<li>Warm air rises to the ceiling [1]</li>
<li>Cool air is denser → sinks / moves towards radiator to replace warm air [1]</li>
<li>This creates a convection current that circulates warm air throughout the room [1]</li>
</ul>
<p><strong>Q6 (6 marks):</strong></p>
<ul class="notes-list">
<li>Vacuum between walls prevents conduction and convection (cannot occur through vacuum) [2]</li>
<li>Silvered walls reflect infrared radiation back into the flask, reducing heat loss by radiation [2]</li>
<li>Stopper reduces conduction through the top of the flask [1]</li>
<li>Overall: all three methods addressed [1]</li>
</ul>
<hr class="section-divider">
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