Making boats

Today we were still thinking of floating and sinking.

We think that heavy things sink and that light things float. 

Teacher had a big heavy shell.

The odd thing about the shell is that it floated if we put it one way but sank if we turned it upside down.

So, how about a ball of marla?

We thought it might sink.  It did!

Is there any way to make it float?

We tried changing the shape of the marla.  We thought that if we made it boat shaped, our ball of marla would float.  We were right (though it sometimes took a couple of goes to get it floating.)

Then we added passengers (peas) and tried to see how many passengers we could put into each boat before they sank.

Some of our boats were really good at floating, even with lots of passengers in them.

33 passengers is a lot in one boat!

Next we tried floating a marla raft.

It wouldn't float at all, not even when we turned up the sides.  We think a raft made of marla doesn't trap any air and that is why it always sinks.  If you want a raft to float we think you should make it out of a material that likes to float (like wood).

Our bests boat of all held 45 passengers!  That seems to be the safest boat to ride in.