Acetone and polystyrene foam

Acetone and polystyrene foam: Is it suitable and safe in a primary school to conduct the activity in which a foam cup is “dissolved” in acetone? Is this a demonstration of a physical change where the foam is just disintegrated and the gas is released? My concerns are both obviously for the use of acetone in an open classroom with primary school students and also if there is anything gaseous/toxic released during the disintegration process.