What happens to shells when we crush them?
3. Collect data and check predictions
Students engage in a three-step investigation. First they collect data on the unbroken shells, then they crush them, then they collect data on the crushed shells to check their predictions. They record data in their notebooks as they go along [Crushing shells claims].
All students will collect data on weight and volume, using the digital scale and the water displacement technique they learned earlier in the unit. Let them know they should collect this weight and volume data first. As time allows, students can collect data to check their predictions about other properties they have chosen to investigate, such as color, size, shape, or smell.
There may not be enough time for every group to gather data to check every prediction. Let students know they should work carefully and not hurry; the class will share their results at the end.
As you circulate among the groups, make sure students collect all the data they need before they crush the shells. Students will need to triple-bag the shells before crushing them, and while they should weigh the shells in the bags, they will need to take them out to collect the volume data (see accompanying note).
A Likely Sequence of Investigation:
- Weigh the shells, along with the three sandwich bags, and record the initial weight.
- Check characteristics such as initial size, color, shape, etc., and record the results.
- Check volume using the water displacement method and record the results.
- Dry the shells with the paper towels.
- Triple-bag and crush the shells by stepping carefully but forcefully on the bag several times. Some shells may not crush easily. These may remain uncrushed in the bag.
- Weigh the crushed shells in their triple bags and record the results.
- Check characteristics such as size of pieces, color, shape, etc. and record the results.
Share class data
Ask students to share their predictions and findings with the class, beginning with the weight and volume findings. As you record the results in a class list, make sure students specify the evidence that verifies or refutes their predictions.
What happened to weight and volume when we crushed some shells?
| Group | Weight | Volume |
|---|---|---|
| 1 | Stayed the same | Stayed the same |
