There are lots of ways for you and your child to explore sinking and floating. One way is by trying to sink things that normally float.
Use objects that you have both agreed are "floaters," like small wooden or plastic toys or certain brands of soap. Or use natural objects like sticks and leaves.
Now place each item in water and after it floats for a minute, invite your child to try to get it to sink.
Are some things easier or harder to sink?
For a real challenge, try sinking a balloon.
Be prepared for some splashing!