GRADE 9 English HEROES AND HEROINES:WORLD – READING:FRICTION Notes
English — Heroes and Heroines: World
Subtopic: Reading — "Friction" (Grammar focus)
These notes look at the grammar you will meet when reading a short scientific passage about "friction". Examples use simple, everyday Kenyan situations (walking, car brakes, tyres). Read each point, see examples, then try the short exercises.
Technical and general nouns in scientific texts:
- Uncountable: friction, force, heat — no plural, often no 'a'. Example: "Friction causes heat."
- Countable: surface, tyre, object — use a/an/the when needed. Example: "A rough surface increases friction."
- Zero article with general truths: "Friction is important in daily life."
Scientific texts often use these tenses:
- Present simple — facts or general truths. "Friction reduces motion."
- Past simple — finished actions or specific experiments. "The teacher measured the force."
- Present perfect — actions with relevance now. "Scientists have studied friction for years."
Use the passive to focus on the action or result rather than who did it. Structure: be + past participle.
- "The experiment was carried out by the students." (past passive)
- "Heat is produced by friction." (present passive)
Use relative clauses to add information about people or things.
- "The shoe that has a rough sole grips the ground better."
- "A surface which is smooth can reduce friction."
Use comparatives to compare two items, superlatives to show the extreme in a group.
- Comparative: "A rough road is rougher than a smooth road."
- Superlative: "Of all these surfaces, sandpaper is the roughest."
Modals express possibility, ability, advice and necessity. Conditionals show cause and effect.
- Modals: "Tyres can slip on wet roads." / "Drivers should check brakes."
- Zero conditional (general truth): "If a surface is rough, it increases friction."
- First conditional (possible future): "If it rains, the road will become slippery."
Use these to make your reading and writing clearer.
- Cause: because, since, due to — "Because the tyre was worn, it slipped."
- Effect/result: so, therefore, as a result — "The surface was wet, so the bike skidded."
- Sequence: first, then, next, finally — good for describing experiments or steps.
Adverbs modify verbs, adjectives or other adverbs and appear often in explanations.
- Manner: "The wheel turned quickly."
- Frequency: "Brakes are often tested before a journey."
- Degree: "Friction is very important."
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Choose the correct article:
a) ___ friction is necessary for walking. (options: A the / B a / C —)
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Change to passive:
"Friction produces heat." → _______________________
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Complete the conditional (zero):
"If the road is wet, cars ________ (slip)."
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Relative clause:
Combine: "The tyre is worn." + "It belongs to the bus." → "The tyre ________ ________ the bus."
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Connector:
Fill: "The surface was smooth, ________ the object slid easily." (so / but)
Answers (click to view)
2) "Heat is produced by friction."
3) "If the road is wet, cars slip."
4) "The tyre that/w hich belongs to the bus." → "The tyre that belongs to the bus."
5) "The surface was smooth, so the object slid easily."
Use these grammar points to notice how the writer organises ideas in the "Friction" passage. Practice by finding examples in the text and rewriting sentences (active ⇄ passive, making conditionals, adding relative clauses).