Set up the lesson with a wedge, a sphere and a wall.
Turn gravity on to roll the sphere down the wedge into the wall.
The wall is moved and/or is knocked over.
Instruct the student to increase the mass of the wall and roll the sphere again at the wall.
The wall does not move.
Create a lesson that demonstrates mass.
Set up the lesson with a wedge, a sphere and a wall. Turn gravity on to roll the sphere down the wedge into the wall. The wall is moved and/or is knocked over. Instruct the student to increase the mass of the wall and roll the sphere again at the wall. The wall does not move.