Vavatch Orbital: Conservation.

We were shown a very amusing video that showed two kids of the same age arguing over whether two equally long pencil were in fact equally long. The experimenters had placed the kids at opposite ends of a table and places the pencils perpendicular to the children, parallel but slightly staggered next to each other. This meant that each child would see that one of the pencils was slightly further away from him than the other - but of course the pencil in question would differ between the two children since they are looking from opposite directions. They were told to decide amongst themselves which pencil was longer, and when they did they would have to call their teacher and put the pencils back in the way they found them....