Note: This lesson has been adapted from Lederman N. & Abd-El Khalick F. (1998). Avoiding de-natured science: Activities that promote understanding of the nature of science. In, Mc Comas W.F. The Nature of Science in Science Education: Rationales and Strategies. pp 83-126, Kluwer Publications.
The aim of this activity is to help the children become aware of how scientists make observations and inferences when examining evidence. The activity also helps children to understand the differences between scientific observations and inferences.
Overview of Lesson:
1. - Put Tricky Tracks “Figure 1” on the white board, or administer a copy of picture to each group. Ask each group (child) to write a short account of what is happening in the picture.
2. - Explain to the children that they are going to be discussing scientific evidence today and that they have lots of knowledge and experience to help them with this task. Put up “Figure 2” on the whiteboard. Ask the children to say what they observe. Record their answers on the board. Typical responses might include “a set of bird tracks, one set of tracks is bigger than the other, a set of animal tracks in the snow”.
However, these are examples of inferences rather than observations. The fact that the children can’t see the birds makes these statements inferences rather than observations. Ask the children can they see the birds? If they can’t see the birds how do they know for sure that these are bird tracks? They could have also have been dinosaur tracks. Explain then that these statements are inferences rather than observations. They are interpreting the evidence (tricky tracks) and using their experiences and knowledge of bird tracks to make sense of and interpret data. An observation is stating simply what you see, for example, “I see two sets of black marks. One set of marks is bigger than the other”.
When they are making observations, they say exactly what they see. All observations should be the same, but inferences can be different. Explain to the children that scientists use both observations and inferences when they are interpreting data. Scientists make observations about evidence and then they attempt to explain their observations. They make inferences. Scientists’ inferences can be different but they MUST be based on the evidence.
3. - Put “Figure 3” on the board, and ask the children to make observations. Again record their responses on the board. Note observations might include, “two sets of black marks, one set is bigger than the other. One is on the right and one is on the left and then there is a section where there are both big and small black marks together in a kind of circle”. This is an example of an observation statement. It is free from opinion and interpretation, it is an objective statement and states exactly what is seen on the overhead. Then ask the children to make an inference. An example, “A big bird and a small bird’s set of tracks. Both birds are heading in the same direction, possibly for some food. The big bird begins to run as the footprints become more spread out”. Reiterate to the children that scientists’ inferences may be different and that this is acceptable. However, their inferences are not wild guesses they must be based on the available evidence. The children’s inferences about the two different sets of bird tracks, possibly heading towards food are based on the pictures (evidence) and on their knowledge of bird tracks in the snow.
4. - Put “Figure 1” up on the board again and ask the children to make observations and inferences. At this stage the children should be becoming more familiar with the differences between scientific observations and inferences. Emphasise the fact that observations they make should be the same, however, their inferences can be different. When scientists (children) are looking at the same piece of evidence (tracks) they can come up with different inferences / ideas for explaining the evidence (pictures).
Different answers are valid as long as they are based on the evidence and are not ‘wild’ guesses. Scientists make inferences when examining evidence in an effort to answer questions about things and their answers must be consistent to the available evidence. However, scientists may never find out the right answer, or what happened as they might not have all the available evidence. Just like us, we can’t be sure whether these are footprints in the snow, nor can we be sure whether the animals were running for food or whether the big animal attacked and killed the smaller animal. We don’t have all the evidence. This is often the case for scientists.
They don’t always have all the evidence, so they are not always in the position to come up with a definitive answer.