Post-It Note Evidence and Explanation
After a couple of activities and readings, you may be ready to ask students to start a public conversation about how the evidence they’ve generated can support or contradict an explanation. One way to do this is to place on the board (or a piece of poster paper) two competing explanations for the phenomenon or puzzling question that you’ve based your unit on. Ideally, one of these can be an explanation that some of your students had originally favored, but is not complete or lacks scientific cohesion. The other explanation should be scientifically coherent, and ideally also generated by your students. Under each explanation is a list of the activities or readings the students have done recently.
Then, in small groups, students are given a prompt (such as a picture) from a lab activity or reading they had done. On this prompt can be some statement about what the key ideas were that students had learned from the activity or reading—this could have been generated by the students themselves when they did the activity. All the small groups can then spend 5 or 10 minutes deciding if what they had learned from that activity or reading supports one or both of the explanations, or if it contradicts one or both of the explanations. If it supports an explanation, they can write on a yellow post-it note why it supports a particular explanation. If it contradicts or does not support an explanation they can use a blue post-it and explain why. At the end of this round a student from each group comes up to the board and in the box that represents that particular activity or reading (below one of the explanations) they can place their post-it note. The teacher then reviews the post-it notes with students and moves on to the next type of evidence. There may be 1 or 2 rounds of this activity during a class period.
The teacher can decide to have a whole class discussion after each round or wait until the final round to engage in this discussion.
This can be repeated two or three times during a unit, and the post-it table can remain up in the room in the interim. Caution! This activity does not, by itself, help kids come up with a rich causal explanation; you should couple this activity with going back to some whole group model or small group models, and have kids periodically re-write or re-draw their causal explanations.
Post-it notes: Comparing evidence about a single explanation
Because the whole idea of talking about evidence can be unfamiliar to students and the idea of comparing two explanations is also challenging at first, you can do the post-it note activity, but use only a single coherent scientific explanation that kids have helped construct. Although it may not represent the full causal story yet, it is helpful to use the students’ explanation to support this activity. The students will participate in the same small group deliberations, but they will focus on whether the evidence they have supports, does not support, or contradicts the one explanation. After the rounds are complete, the teacher can have a summary discussion in which gaps in the students’ explanation are questioned, in addition to seeing what evidence has supported the explanation.
This can be repeated two or three times during a unit, and the post-it table can remain up in the room in the interim.
Caution! This activity does not, by itself, help kids come up with a rich causal explanation; you should couple this activity with going back to some whole group model or small group models and have kids periodically re-write or re-draw their causal explanations.
Watch Suzanne talk about how she used the Post-it strategy with middle school students in a unit on yeast and cellular respiration.