Water experiments

We are learning a lot about water.

We know that water has a skin on the top called "water tension".  Pond skater insects can stand on this water skin but we can't because we are too heavy.

 We filled up a plastic bottle, put a hand on top, turned it over and then took the hand away.

Do you think the water spilled out or stayed in the bottle?

We had to guess. Most of us guessed it would spill but some guessed it would stay in the bottle.  It didn't! but came rushing out when we pulled our hand away.

 Now we tried again, but this time used some card to cover the opening of the container.  We were very surprised at the result.  When we took our hand away the card didn't fall down.  We were amazed.  Teacher explained that the air trying to get into the container pushes against the card and stops the card from falling, even though the water in the container is trying to get out.

 Now for something really cool!  If you cut a small boat out of card and put it in the water it will float.  The boat will not move though.  Now if you put a drop of wash up liquid (or soap or shampoo) at the back of the boat, the boat will speed away.  Be warned.  This experiment works only once until you empty the soapy water, clean the container and start again)  The soap breaks the skin (surface tension) of the water and pushes the speed boat along.  We can't wait to try this in the bath.

Just before home time we tried the diver experiment. 

Our diver floated ok but this diver is too light so he wouldn't dive for us.  Teacher will make him heavier by adding more marla and we will try and get him to dive tomorrow.