Set up a simple marble run with a designated endpoint but build the track so that the marble doesn’t make it to that endpoint.  Encourage children to solve the problem.

Adaptations are built into this investigation.

Marble run can be built on a table or on the floor, whatever is easiest for children to access.

If marbles are a choking hazard or difficult to grasp, you can use ping pong balls or other larger objects to put down a maze made from found objects like toilet paper rolls, PVD pipe, etc.

If children struggle to improve the marble track, encourage children to experiment with changing the track and noticing how the movement of the ball changes.