The Nature of Science strand

Physical World

Students explore the role of multiple trials in producing reliable data.

In Zoom, Zoom! students investigate the motion of toy cars travelling down ramps. The existing activities require students to fill in charts showing the distance travelled for three separate trials and the average distance. The Teachers Notes’ suggest discussing why averages are useful when analysing data. This adaptation delves more deeply into that idea.

Adapting the resource

Before the students begin to record their data in the charts, ask:

• Why do you have to do more than 1 trial with each car? [To minimise the risk of a “bad” result.] Brainstorm all the possible things that could produce a “bad” result. [The car might flip over, it might hit the edge of the ramp, the weight might fall off, the amount of push given to one car might not be the same as the push given to the other cars, the measuring could be wrong etc]
• How many times would you want to repeat a trial to be sure you could trust the result? [Answers will vary – generally more trials will produce more reliable results. Look for how students justify their answers.] Is there a point where increasing the number of trials does not affect the average?
• When might it really matter to get an accurate result? [Answers will vary but look for an understanding that in some research, e.g., where human life might be put at risk, it is important that we get reliable results.]
• Averaging the distances travelled over three trials is one way of trying to get a reliable measurement. How else might we do this? [Example: Doing more trials and finding out what the median is.]

In order to evaluate the trustworthiness of data students need to know quite a lot about the qualities of scientific tests so they know what questions to ask. They also need a reasonable level of statistical literacy. It is not enough just to know how to do a “fair test” – students need to know why protocols such as repeated trials, controlling variables, accurate measurements, etc., are important.

Developing an appreciation of how evidence in science is generated supports students to become scientifically literate, i.e., to participate as critical, informed, and responsible citizens in a society in which science plays a significant role. (This is the purpose of science in NZC.)

Can students give reasons for multiple trials when investigating?

Do they understand that how the data are gathered affects the trustworthiness of the data?

For suggestions about adapting tasks in ways that allow students to show progress in critiquing evidence see Progressions .

This adaptation could be used whenever students are carrying out investigations – regardless of the context. Science Fairs would provide a rich context.

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