How much heavier is one cube than another?

Invite students to add their personal objects to the weight line.

Consider the results. Are some personal objects too heavy for the line to accommodate? Can students estimate where those objects might be placed? Between which two cubes do most of the personal objects fall? Are there gaps, i.e., places where we find very few personal objects or none at all? Ask,

• If each of you had another object to add to the line, and each of those objects weighed less than the copper cube, would there be a place on the weight line for each of those objects?

If students say “no,” ask for specific examples.

• If you have an object that weighs less than the copper cube, what could it weigh so that there would be no place for it on the line?

Wrap up the strand by asking a couple of open-ended questions about the nature of weight.

• What is the smallest amount of weight you can imagine an object having?
• Could two objects be so close in weight that we could not measure the difference?
• Where does the weight line end?
• What is weight, anyway?