Materials: Balls, a board (or cardboard, or a table with 2 legs higher), blocks or something to directly the balls down the board.
Lay out your board so it is slanted enough for a ball to roll, but not so much that the blocks won't sit on the board. Ask your child to roll the ball down the board. How do you know which end is the top? Give your child the blocks and ask them to change the direction the ball rolls using the blocks. You can even put a target at the end (a bowl or other item) that they can get the ball to roll into.