I got this from Jim...

Grant was supposed to be looking for the keys to his mother's car. I
suspected that he might have left them in the garage or even locked them
in the car so I took him out to look for them. But instead of looking
for the keys he grabbed a baseball bat and began walking around the
garage banging the bat on the concrete floor. After a minute or so of
this apparent diversion I said, "Grant! Are you helping to look for the
keys?"
He replied, "Yes. If I bang on the floor the keys will vibrate and I
can hear them."
Clearly this boy is meant to become a physicist.
Dad