Year 8 Science · Unit 4 · Lesson 6

Identifying Trends, Relationships and Patterns

Challenge Worksheet

Name

Date

Class

Learning Goals

Follow a causal reasoning chain through enzyme reaction data to reach a scientific conclusion.
Evaluate the conditions under which a small number of data points can or cannot support a reliable conclusion.
Distinguish between interpolated and extrapolated conclusions and assess confidence in each.

Warm Up

Because… chain

An enzyme experiment collected reaction rate data at five temperatures. Follow the cause-and-effect chain below. Fill in the four missing effects — each cause leads directly to the next step.

Data collected at 20°C, 30°C, 37°C, 45°C, 60°C shows reaction rate increasing from 20°C to 37°C

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Reaction rate reaches its highest point at 37°C

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Above 37°C the reaction rate begins to fall (45°C) and drops sharply at 60°C

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37°C is normal human body temperature

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Overall conclusion about this enzyme's optimal temperature:

Go Deeper

Evaluate — how many data points are enough?

The claim

After collecting data at only 3 temperatures (20°C, 37°C, and 60°C), a student says: "I can clearly see the trend from my three data points — the enzyme works best at 37°C and I can predict the exact reaction rate at 50°C from my graph." Their teacher responds: "Three points can sometimes be enough — but not always, and your confidence in that prediction matters."

Respond to each question below with a full, reasoned answer.

(a) Under what conditions is 3 data points sufficient to support a trend conclusion? When does 3 data points become a serious problem? Use examples from the enzyme experiment in your answer.

Challenge 4 marks

(b) The student wants to predict the reaction rate at 50°C (beyond their highest measured temperature of 37°C success, before 60°C). Is this an interpolation or an extrapolation? Explain how this affects how confident the student should be in their prediction.

Challenge 3 marks

(c) A classmate adds data from 45°C and discovers the reaction rate there is much higher than the graph predicted from 3 points. What does this reveal about the danger of drawing a smooth curve through only 3 data points? What should the student have done differently?

Challenge 3 marks

Wrap Up

In one sentence, what was the main idea of this lesson?