Sinking and floating

At not-quite-3, my son has already got the idea that in water some things sink, and other things float.  He's had various objects to play with in the bath, from 'proper' bath toys to empty bottles and random objects from around the house that we haven't stopped him taking in for a wash. He's also watched Maddie Moate's song about sinking and floating a few too many times (I have to stop myself singing along...)! 

I decided to make sinking and floating into a game he could play fairly independently late one afternoon when I needed to cook. I took a washing up bowl of water, and a set of kitchen objects and asked him to find out whether things sink or float. Initially this seemed a stroke of brilliance because he loved it, and I got as far as chopping things up. Then he kept asking for more things to put in the bowl and I spent as much time trying to locate things he could put in water as actually cooking. By the time dinner was ready, the bowl was pretty full and I was getting short of ideas (and wooden spoons).

Since then, I've been asked to play the sinking and floating game a few more times. We've branched out into objects found in other parts of the house and garden. Some that have captured his imagination are stones, coins, an allen key, a big glass marble, a satsuma, a plastic straw, grapes and dried pasta.  We've also made little boats from aluminium foil scraps to float coins and other small objects that otherwise sink.

We tried it as an outdoor activity today too, and it worked well, although a slightly muddier array of objects from around the garden were tested!

Does it sink or float?

It's been fun to talk about new objects, getting him to predict whether he thinks they will sink or float and watching him find out if he's right.  It's nice to see him making an informed guess and explaining why he thinks something will sink or float, and then mostly being proved correct, but sometimes being surprised - for example, a wooden peg floated, but a plastic one that looked otherwise very similar sank. I've avoided the word density, but we have talked about how some things feel heavy for their size and others feel light, and that it's not just about their weight (i.e. stones of any size sink).