Which of these shapes can roll? a), b), c), or d).
A good way to imagine this is to think about what would happen if we placed each of the shapes on a slope. What would happen if we put shape a on the slope and pushed it? How would it move? How would it get to the bottom?
This shape would slide down the slope. So shape a can’t roll because it slides. Shape b, the cube, would also slide down the slope. Shape b can’t roll. It slides because all of its sides are flat.
What happen to shape c if we pushed it down the slope? Shape c would roll down the slope. This is because its sides are curved.
Shape c can roll because it has a curved face. The other shapes have flat sides. So they would slide.