How can we compare the volumes of liquids?
2. Predict volume order
Distribute a tray of materials to each group.
Encourage students to discuss the challenge in their groups and brainstorm strategies. They can use any strategy they want as long as they keep the liquids in their original containers.
As you circulate among the groups, ask students explain their strategies. Model three-dimensional thinking whenever you can, e.g.,
- So, you're thinking that because this container is wider than the others, it might hold more water, even though the height of water in the other containers is a bit higher.
- You're going to wrap your hands around the containers to get a sense of how much space the water takes up. Is that right?
As students arrive at their predicted volume order, they should record it in their notebooks [Which water sample takes up more space?], using the letters on the containers. Record the volume orders in the class table you have prepared.
| Group | How do the three volumes compare? Least Volume ––––– Greatest volume |
|---|---|
| 1 | |
| 2 | |
| 3 | |
| etc. |
Is there agreement about the volume order or are the results quite varied? It is not necessary to come to consensus now; students will determine the true volume order in a minute.
Height isn't everything. Volume is a three-dimensional measurement, but when containers are identical, we need only look at height to compare volumes. This habit can be hard to break, and students may need to be reminded: Volume is space in every direction; volume is 3-D space.
