How are these four facts connected?



• Cells are small.

• When you get cold, you hold your arms against your body.

• Elephants have big, flat ears to help themselves stay cool.

• Flatworms live in oceans, ponds, and streams. The ones in oceans can be up to a foot long, but flatworms are always very flat. These animals have no blood, heart, or lungs, yet they have no trouble getting oxygen to their cells.