This was the simpe machine students were most excited about. Who knew?
As a group we discussed what a pulley is, what the physical properties are, and what simple machine it reminded them of (wheel and axle). I introduced them to a fixed pulley, movable pulley, and complex pulley, one at a time. I showed them a drawn visual, then showed them the set up with actual pulleys and string. After demonstrating they went in their groups to try it on their own. With each pulley, they measured on a spring scale, the force in grams it took to lift a waterbottle.