CHILDREN AND PHYSICS--"Does a child's first conception of velocity include comprehension of it as a function of distance and time, or is his notion more primitive and intuitive? Albert Einstein himself posed this question to me in 1928 when I was demonstrating some experiments on causality to him one day. I have since performed a very simple experiment which shows that a child does not think of velocity in terms of the distance-time relation. We place before the child two tunnels, one of which is obviously much longer than the other, and then we push a doll through each tunnel with a metal rod in such a way that the dolls arrive at the other end of both tunnels simultaneously. We ask the child:
'Is one tunnel longer than the other?'
'Yes, that one.'
'Did both dolls go through the tunnels at the same speed, or did one go faster than the other?'
'The same speed.'
'Because they arrived at the same time.'