Imagine you need to lift a heavy school bag onto a high shelf. Pushing straight up is hard work. What if a tool could change the size or direction of your push so the bag felt lighter?

Today we build two simple machines, a lever and a pulley, and feel what they do to the effort. Hands up: which do you think will make the lift feel easier?

Today we start with two words.

Watch the lever demo. Where should the pivot go to make the lift feel easier?

First: build a lever at your table.

1. Rest a ruler on a pencil pivot.
2. Put the small load on one end.
3. Press the other end with one finger.
4. Try the pivot near the middle, then nearer the load. Notice how hard you push and how far your finger moves.

Next: try the pulley at a station.

A pulley is a wheel a string runs over.

1. When your group is called, go to a pulley station.
2. Tie one end of the string to the load. Pull the free end down.
3. Does the load rise? Does the pull feel easier, harder, or about the same — and which way are you pulling now?

Lever claim: with the same load, which pivot place made the push easier, and did your hand move a short way or a long way?

Pulley claim: lift the same load once by hand, then with the pulley. Are you pulling up or down on the pulley? Did the effort feel less, more, or about the same?

For each machine, note: the load, what you changed, whether the effort felt less, more, or about the same, and anything you noticed about distance or direction.