Year 9 - Science
Understanding time scales
Adaptations, competition, natural selection and evolution
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit explores variation within and between species, competition, and natural selection. It focuses on asking questions, making predictions, planning scientific enquiries, and testing hypotheses. It also covers analysing results, explaining findings, and identifying new questions that arise.
Lesson Summary
You will learn to describe key events in the history of Earth and distinguish between billions, millions and thousands of years ago.
Key Notes
- Evidence suggests Earth was formed 4.5 billion years ago (one billion is one thousand million).
- Evidence suggests the first living organisms (microorganisms) appeared around 3.8 billion years ago.
- The oldest fossils are around 3.5 billion years old, and the newest fossils are around 10 thousand years old.
- Evidence suggests the first land plants appeared 500mya, the first mammals 200mya, and modern humans 350k years ago.
- Scientists divide Earth's history into eons, periods and epochs to make it easier to understand.
Vocabulary To Learn
- billion: One billion is one thousand million (1 000 000 000).
- thousand: One thousand (1000) is equal to 10 × 10 × 10.
- million: One million is one thousand thousand (1 000 000).
- evolution: The characteristics of species gradually change over time, sometimes forming new species. This process is called evolution.
- extinction: Extinction is the permanent loss of a species.
Common Mistakes To Avoid
- Students struggle to comprehend absolute ages of key events in the history of Earth and evolutionary history.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
Evidence suggests Earth was formed 4.5 billion years ago (one billion is one thousand million). Evidence suggests the first living organisms (microorganisms) appeared around 3.8 billion years ago.
2. Define this scientific word and use it in context. 'billion'
One billion is one thousand million (1 000 000 000). Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Students struggle to comprehend absolute ages of key events in the history of Earth and evolutionary history. Correction: This lesson provides many examples and context to give students a sense of the differences in time scales involved in the history of Earth and evolution.
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