During construction week in the preschool classroom, the students learned and experienced what a pulley is. We tied a string around the handle of the tool box. (That was the best thing with the sturdiest handle we had to use but you could also use a sturdy bucket with a handle.)
We put the box on the other side of our half wall with the string hanging over on our side of the wall. The students worked and pulled until the box came up to the top of the wall for them to reach it.