Phun in Physics

I mentioned my physics teacher on last post. She was a star among teachers. 

One fine spring day she introduced this experiment. 

She gave each pair of us a large test–tube half full of water, an ice cube and a bit of metal gauze to hold down the ice underwater. She wanted us to determine the displacement of the ice, in ccs, towards a proof that water expands when frozen.

Ten minutes later she asked how we were getting on. Our results were crazy, haywire, all over the shop. We struggled on.

Five minutes after that she couldn’t hold it in any more, and started laughing. “Enough, enough!” she said, struggling for breath. “Don’t you know what day it is?”

The first of April, and not one of her allegedly bright young girls had twigged.