This was actually a couple of weeks ago. Kora was studying simple machines: inclined planes, levers, pulleys, wheels and axles, etc. This project is an oldie but a goodie. And the younger kids were so excited to get to participate in Kora's science project.
The rope wrapped around the broomstick handles acts as a pulley with every wrap. Aubrey and Brynna are trying to hold the broom sticks apart and Kora is pulling on the rope trying to pull them together.
Now we wrapped the rope to create two more pulleys. Kora nearly pulled them over, it was so much easier this time.
I couldn't get a picture of it, but then we let Hailey try to pull the brooms together with Kora and I (the two strongest people in the house at the time - Kelly was at work) holding them apart. Hailey could pull us together with 5 pulleys though not with three.
They really had fun with this, being able to be stronger than Kora and I. Sad thing is they probably will all be taller and stronger than I am when they grow up!