When the can is heated, the air goes out of the can and
it fills with water vapor. When the can is allowed to cool
with the cap on, the water vapor condenses and air wants
to get back in. But since air can’t, the pressure inside the
can is less than outside the can, and the air outside pushes
on the can and it crinkles. (Spring 1997)
The steam is what fills it right now, but if that turns back
to water the pressure has gone down inside but stayed
the same outside. It wants to be equal so it will crush
the can to make it equal. (Spring 1997)
The variety of responses led us to wonder if there were
not a better way to communicate the particulate nature of
matter to students. Instruction using chalkboard drawings
and colorful transparencies did not appear to be adequate.
We decided that developing an animation depicting the behavior
of gas particles in the can-crushing demonstration might
be helpful. Several chemical education researchers have shown
that computer animations can facilitate the development of