As part of the science exhibition the kids were using Cartesian divers and I felt that we were missing the part of making one ourselves. That morning on my walk with Shifu (I found a straw on the road), a shampoo bottle cap from the trash and borrowed modeling clay from Arham and set out to make some Cartesian divers.
Looking at these divers the kids felt that they could really make it their own and returned my (purchased and self made divers) and committed to make one themselves for their presentation.
In the straw model I put a hole on one of the ends (I remember seeing something like this on instructables). In both cases you add enough clay to just make the object float.
An interesting conversation started in the class regarding the relative speeds of the different divers.
At my other school the kids made a bunch of divers with pen caps and by the end of the class, there was a litter of caps floating (and sinking) in the bottle we had.
When I got home I thought I would show Arham what Appa made. He found it on his own and set things right, calmly removing the clay that had accidentally made it there and put back in its proper place, his clay box :).