Ms. Frobisher is giving the student who can put the ball in the bottle, without breaking the glass or destroying the ball somehow, an iPOD.

In her room, there is a microwave, petroleum jelly, a stove, and a freezer.

Six of the seven students make unsuccessful attempts to accomplish this feat.

Now, the seventh student Gavin comes up to the bottle and the ball. He thinks of using one of the tools in Ms. Frobisher's room at his disposal and uses one (not the jelly as it was already proven to not work) and five hours later, gets the ball in the bottle and his free iPOD.

How did Gavin do it?

If both are in the freezer, at some moment the ball will fall suddenly, possibly breaking the glass, which would probably be more brittle at freezing temperature.