Tricky tracks

This resource accompanies the article Show students how to grasp the scientific process in Education in Chemistry where you will find more ideas and tips. It was originally published in Nature of Science alongside two other activities to introduce the scientific process.

Learning objectives

1. Distinguish between observation and inference.
2. Recognise that scientific theories develop over time when new evidence becomes available.

Introduction

When drawing a conclusion, scientists need to take care that it is consistent with the evidence.

As part of this learners need to know the difference between an observation and an inference. This activity assumes the following definitions:

• An observation is what is actually seen.
• An inference is interpreting what is seen.

Sometimes new ideas or evidence come along which do not fit existing scientific theories. Then, more experiments have to be carried out to see if the new idea is correct.

How to use the resource

This activity will fit into a scheme of work for learners aged 11–14 anywhere where experimental observations are made. It can be used before a class practical which requires careful observation, followed by interpretation. For example, the reaction of metals and acids, or reactions of carbon dioxide.

This activity could be carried out as a whole class exercise. Learners may record their answers working individually using the student worksheet or in groups of three to four. The subsequent discussion is key to learners developing the understanding.

Timing

50–60 minutes. Approximately half the time should be used for learners to answer the questions and the rest of the time discussing the answers.

Lesson plan

1. Introduce the activity in context (slide 5) and show Tricky tracks 1 to the class (slide 6). Give the class 5–10 minutes to answer question 1, individually or in small groups.

2. Show Tricky tracks 2 (slide 7) and Tricky tracks 3 (slide 8) and give learners ~10 minutes to answer the questions.

3. Feedback to the whole class some answers to question 1, by asking different learners to read out their accounts. Try and get as many different explanations as you can. It is important to accept all explanations equally.

4. Go through questions 2–4 using the answers below as a guide and pointing out the difference between observation and inference.

5. Return to Tricky tracks 1 and ask learners to answer question 5 (slide 10) focussing on observation only.

6. Finally, link this exercise to science in the real world, saying that scientists often make similar inferences as they try to interpret their observations. There may be several equally valid theories until new evidence comes along to change it. Follow up with questions 6 and 7 (slide 11).

Differentiation

To provide additional support for learners you could come back together as a whole class group to answer the more demanding questions, such as 3 and 7.

Answers

Find suggested answers and a guide to discussing the answers with your class in the teacher notes.