Basic 8 · Science · Term Revision
Term Revision in Science
In this topic you will recall and summarise what you have learned this term about mixtures, cycles, teeth, energy, heat and electricity, and practise end-of-term questions.
By the end of these notes you should be able to:
- Recall key ideas on mixtures and cycles
- Recall key ideas on teeth and energy
- Answer end-of-term questions
What you already know
- All topics covered in Science this term
Copy everything that has a blue line on its left into your notebook. The other parts are for reading.
Lesson 1
- Strand
- Revision
- Sub-strand
- Term Revision
Introduction
Good revision organises facts into a clear pattern. Let us begin with mixtures and cycles.
1. Mixtures
| Idea | Key points |
|---|---|
| mixture | physically combined, parts keep properties |
| homogeneous | uniform throughout |
| heterogeneous | not uniform |
| solution | tiny particles, does not settle |
| suspension | large particles, settles |
| colloid | medium particles, scatters light |
2. Separation Methods
| Mixture | Method |
|---|---|
| sand and water | filtration |
| salt from sea water | evaporation |
| pure water from salt water | distillation |
| camphor and sand | sublimation |
| dyes in ink | chromatography |
| oil and water | separating funnel |
| crude oil | fractional distillation |
3. The Carbon Cycle
Photosynthesis takes carbon dioxide out of the air. Respiration, decomposition and combustion return it. Carbon is stored in the air, living things, soil, oceans and rocks. Burning fossil fuels and cutting forests add carbon dioxide to the air, causing global warming. Trees, clean energy and less waste can help.
4. The Mosquito
The Anopheles life cycle has four stages: egg, larva, pupa and adult. Only the female sucks blood. She carries the Plasmodium parasite, which causes malaria. Malaria reduces income and learning, and costs a great deal to treat. Control it by removing stagnant water, using treated nets and getting tested and treated early.
5. Making Links
Use one example for each idea, such as salt pans for evaporation. An example from your own community is easier to remember than a definition learned by heart.
New words
- concept map
- A diagram linking ideas.
- recall
- To bring back to mind.
- summarise
- To give the main points.
- revise
- To study again.
Summary
- Mixtures are classified by uniformity and particle size.
- The separation method depends on properties.
- Carbon and the mosquito both follow cycles.
Class activity: Separation Match
- Write mixtures and methods on cards.
- Match them.
- Explain each match.
You need: Beaker, Hand lens, Safety goggles
Exercises
Answer in your exercise book first, then check your answers.
1. Milk is a…
- A. colloid
- B. solution
- C. compound
- D. element
Show answer
Answer: colloidScatters light.2. Salt from sea water is obtained by…
- A. evaporation
- B. filtration
- C. sublimation
- D. magnets
Show answer
Answer: evaporationSalt pans.3. Respiration releases carbon dioxide.
- A. True
- B. False
Show answer
Answer: TrueCycle.4. Malaria is caused by the parasite ______.
Show answer
Answer: PlasmodiumDisease.5. List the four stages of the mosquito life cycle.
Show answer
Answer: Egg, larva, pupa and adult.Cycle.6. Give two ways humans disturb the carbon cycle.
Show answer
Answer: Burning fossil fuels and deforestation.Impact.
Lesson 2
- Strand
- Revision
- Sub-strand
- Term Revision
Introduction
Teeth and energy might look like different topics, but both show how structure is linked to function.
1. Teeth
| Idea | Key points |
|---|---|
| parts | crown, neck, root; enamel, dentine, pulp, cement |
| types | incisors cut, canines tear, premolars and molars grind |
| sets | 20 milk, 32 permanent |
| decay | bacteria plus sugar make acid that attacks enamel |
| gum disease | plaque causes gingivitis, then periodontitis |
| prevention | brush, floss, eat well, visit the dentist |
2. Energy
| Idea | Key points |
|---|---|
| forms | kinetic, potential, chemical, electrical, heat, light, sound |
| conversion | one form changes to another |
| conservation | energy is not created or destroyed |
| renewable | solar, hydro, wind, biomass |
| non-renewable | coal, oil, gas, nuclear |
| sustainable | use without harming the future |
3. Heat and Electricity
Heat is energy that flows from hot to cold, while temperature measures how hot something is. Heat moves by conduction, convection and radiation. Electricity is generated, stepped up to high voltage to reduce losses, transmitted by GRIDCo, stepped down and distributed by ECG and NEDCo to users at about 230 V.
4. Links Between Topics
Science topics are linked. Burning charcoal is a chemical energy change that also adds to the carbon cycle. Water treatment uses separation. Akosombo connects energy conversion, transmission and the environment. As you revise, try to see these links, since they help you to remember and explain ideas.
5. Linking Science to Health
Remember how teeth, malaria and water all link to health. Good habits protect you, and they also save your family money.
New words
- function
- The job something does.
- structure
- How something is built.
- conversion
- A change from one form to another.
- link
- A connection between ideas.
Summary
- Tooth structure relates to function, and hygiene prevents decay.
- Energy is conserved and converted.
- Electricity is transmitted at high voltage to reduce losses.
Class activity: Topic Links
- Choose two topics.
- Write three links between them.
- Share them with the class.
You need: Beaker, Hand lens, Safety goggles
Exercises
Answer in your exercise book first, then check your answers.
1. Incisors are used to…
- A. cut food
- B. grind food
- C. tear meat
- D. store food
Show answer
Answer: cut foodFront teeth.2. Which is renewable?
- A. wind
- B. coal
- C. oil
- D. gas
Show answer
Answer: windNatural flow.3. Energy can be destroyed.
- A. True
- B. False
Show answer
Answer: FalseConservation.4. Heat moving through a solid is called ______.
Show answer
Answer: conductionTransfer.5. State the causes of tooth decay.
Show answer
Answer: Bacteria in plaque feed on sugar and produce acid.Decay.6. Explain how energy is converted in a solar lamp.
Show answer
Answer: Light to electrical energy, then chemical storage in the battery, then electrical to light.Chain.
Lesson 3
- Strand
- Revision
- Sub-strand
- Term Revision
Introduction
Practice shows you what you know and what you still need to review.
1. Sample Questions
Practice question 1
Describe how to obtain clean water from muddy water in the laboratory.
- Let the mud settle.
- Decant the top water.
- Filter it through filter paper.
- Boil or distil it to kill germs and remove dissolved substances.
Answer: Settling, decanting, filtering, then boiling or distilling
Practice question 2
A device receives 200 J of energy and gives out 50 J of useful energy. Find the efficiency.
- Efficiency = 50 ÷ 200 × 100%.
Answer: 25%
Practice question 3
Why are power lines at high voltage?
- High voltage means less current for the same power.
- Lower current means less heat loss.
Answer: To reduce energy losses
2. Answering Practical Questions
When a question asks you to describe an experiment, list the apparatus, give steps in order, state what you observe and draw a conclusion. Draw clear, labelled diagrams with a sharp pencil. Use units in your answers, and show all calculation steps. Marks are often given for correct method, even if the final answer has a slip.
3. Command Words
| Word | Meaning |
|---|---|
| state | give a short answer |
| describe | say what happens |
| explain | give reasons |
| compare | give similarities and differences |
| calculate | work out with numbers |
4. Preparing for the Vacation
During the vacation, keep looking at science around you. Watch how salt forms, keep your compound free of still water and brush your teeth twice a day. Reading ahead will help you start next term with confidence.
New words
- command word
- A word telling you what to do.
- diagram
- A labelled drawing.
- apparatus
- Equipment used.
- unit
- A standard of measurement.
Summary
- Practise questions from every topic.
- Follow command words and show working.
- Keep applying science in the vacation.
Class activity: Mock Test
- Answer ten mixed questions.
- Mark your answers.
- Write two topics to revise.
You need: Beaker, Hand lens, Safety goggles
Exercises
Answer in your exercise book first, then check your answers.
1. Which word asks for reasons?
- A. explain
- B. state
- C. list
- D. name
Show answer
Answer: explainCommand word.2. Efficiency of a device giving 30 J from 60 J is…
- A. 50%
- B. 30%
- C. 20%
- D. 200%
Show answer
Answer: 50%30 ÷ 60 × 100.3. Diagrams should be labelled.
- A. True
- B. False
Show answer
Answer: TruePractice.4. "Calculate" means to work out with ______.
Show answer
Answer: numbersCommand word.5. How do you describe an experiment in an examination?
Show answer
Answer: List the apparatus, give the steps, state observations and draw a conclusion.Practical.6. Plan how to make muddy water safe to drink.
Show answer
Answer: Allow it to settle, decant, filter and boil it.Water.
Homework
- Write a one-page summary of the term's science topics.