You have a block, and you see that it floats in water.

What could it be made of?

Block #1

What do you think will happen if you make a bigger block out of the same

material? Will it float or sink?

Maybe light plastic, like a lego. (temporarily) If it was bigger though, it'd sink

Explanation:

Most Lego bricks are made of ABS plastic which has a specific gravity greater than 1 (but only slightly). So, they are heavier than water and will not float naturally. You can get small bricks to float initially since small bubbles cling to their surface, but they will all sink eventually.