Purpose of the discussion

The purpose of this discussion is to bring forward three big ideas about matter and weight:

• The 4 materials had the same weight but each material took up a different amount of space.
• When a 10g sample of a material was reshaped, the weight didn’t change.
• The combined weight (the completed object) equaled the sum of the individual weights.

Engage students in the focus question

What did you discover about weight as you did the 10-10-10-10 challenge?

Have teams bring their objects to the group. Ask the students what all their objects have in common. Discuss the following:

• how some materials take up more space than others, even though they weigh the same
• whether the weight of the original material (10 grams) changed when it was reshaped
• whether the total weight of the object equals the sum of the parts

Can students extend this last concept for everyday objects? For example, what can they say about the weight of a wood–handled hammer [the weight of the steel plus the weight of the wood will equal the weight of the whole hammer], or steel scissors with plastic handles, or a pair of metal–rimmed eyeglasses?

If possible, leave the objects in a gallery space for reference during the next set of investigations on volume.