You may be used to crushing can using your foot or hand. Have you crushed it using an implosion? If the water in a can be heated to reach its boiling point and then dipped by inverting in a cold bowl of water, this would create a vacuum and result in decreased vapor pressure resulting in crushing of the can (implosion). In this experiment, due to an imbalance of pressures between the outside and inside surroundings of the can, implosions happen. This activity can be explored by students under adult supervision.
The video also includes some additional easy and kids friendly activities to understand the concept of balanced and unbalanced forces hands-on.
This video satisfies the 3-PS2-1 requirement for third-grade science proficiency.
Students who demonstrate understanding can:
3-PS2-1. Plan and conduct an investigation to provide evidence of the effects of balanced and unbalanced forces on the motion of an object.