Extension ideas for sink and float

You can do all of these activities outside on a much larger, messier scale if you want to!

• Use all natural found materials - you could do this in a pond/stream as you are out and about also.
• Collect different types of 'boats' such as a metal jam jar lid, coffee lid, matchbox covered in tin foil etc and put a box of metal washers/nuts etc with it; see how many washers/nuts you can get into each boat before it sinks and talk about what happens. 
• You could use marbles with boats also, these are interesting as they roll around and can cause the boats to sink as they all gather on one side!
• Collect different shapes and sizes of leaves and very small pebbles and float a leaf, trying to put as many pebbles on as possible.
• Put a lump of plasticene or bees wax with a small bowl of warm water. When you drop the lump in it sinks, but if you warm it and fashion a small boat shape out of it, it will float!
• Have a collection of all different types of one object such as balls (tennis, golf, ping pong, marble etc) or spoons (metal, plastic, wooden, slotted).

Some books you may find useful to take this idea further:

• Making Things Float and Sink (Fun Science Projects)
• Float and Sink (First Step Forces and Motion)