How can we measure the volume of a liquid?
4. Make meaning
Purpose of the discussion
The purpose of the discussion is to replicate what was done in words, including giving a rationale for the methods used to build a measuring cup. This will help students consolidate their learning and you will gain insight into what they are taking away from today's investigation. Return to the investigation question for discussion: How can we measure the volume of a liquid?
Engage students in the focus question
- This was a busy investigation with lots of steps. Does it all make sense to you? Pretend a visitor has come into the room and has no idea what you just did. How would you explain today’s work?
Do students touch on all the following points as they describe their work:
- In science, a standard unit of measure for volume is cubic centimeters.
- We can use centimeter cubes to help us measure or estimate volume.
- We can use a measuring cup to measure liquid volumes.
Are they able to answer the investigation question:
How can we measure the volume of a liquid?
Summarize the discussion and recap the investigation
Let students know that as they work with more liquids, they’ll be able to use the measuring cup they made and will get better at estimating volumes. For example, imagine a can of soda. Is it more or less than 140 cubic centimeters (the capacity of the measuring cups they just made?) Based on today’s experience with cubic centimeters, what do they think the volume of a can of soda might be?
Cubic confusion? Some students may be having trouble making the mental transition from centimeter cubes, which are solid physical objects, to cubic centimeters, units that can be used to measure liquid volumes. It might help to explain it this way: We describe the volume of things using the words cubic centimeters even when we can’t see cubes at all. If we have a good measuring cup, and we pour juice into it, and see that it reaches the level of 60 cubic centimeters, we know we have 60 cubic centimeters of juice, because its volume is the same as 60 of those centimeter cubes, and not because the juice looks at all like a cube.
