Year 9 Science · Unit 4 · Lesson 19

Evidence and Scientific Explanations

Foundation Worksheet

Name

Date

Class

Learning Goals

Classify examples as strong evidence, weak evidence, or not evidence at all.
Recall the key features that make scientific evidence trustworthy (reliability, validity, sample size).
Distinguish between primary and secondary sources of evidence.

Warm Up

Sort it!

Write each item from the pool into the correct category box. Each item belongs in exactly one box.

Peer-reviewed journal article with 500 participants One student's single trial experiment "My friend told me it works" 5 independent experiments reaching the same conclusion Manufacturer's own product trial with no control group CSIRO dataset of 10 years of wave height measurements A TV advertisement claiming the product is "scientifically proven" Systematic review of 30 independent replications A rumour posted on social media A textbook chapter citing multiple peer-reviewed studies

Strong evidence

Weak evidence

Not evidence

Your Turn

Fill the gap

Choose the correct word from the word bank to complete each sentence about what makes scientific evidence trustworthy.

evidence primary secondary reliable valid peer-reviewed explanation opinion hypothesis

Scientific is information gathered through observation or experiment that is used to support or refute a claim. When you collect data in your own experiment, that is called evidence. Data from published textbooks and studies is called evidence.

For evidence to be , it must give consistent results when the experiment is repeated. For evidence to be , the experiment must actually measure the thing it claims to measure — not some other variable by accident.

Research published in a journal has been checked by other expert scientists before being accepted. Evidence alone is not enough — you also need a scientific that links the evidence to a concept such as Newton's Laws or the wave equation.

Show What You Know

1. Give one example of primary evidence and one example of secondary evidence a student could use when investigating how ramp angle affects the speed of a toy car.

Recall 2 marks

2. Why is a single trial not considered strong evidence in a scientific investigation? Give one reason.

Recall 1 mark

Wrap Up

In one sentence, what is the difference between strong and weak scientific evidence?