Simple machines: hammering nails outside, building ramps, levers, pulleys, block and tackles, lifting cars with the screw of a jack, wedging things up, open, and in, exploring the impact of wheels on friction and force, gearing up for inventing and the invention fair: that's spring in grade 4!
Mnemonic: I Want Popcorn When Sam Leaves
Inclined Plane, Wheel and Axle, Pulley, Screw,Wedge, Lever (and Gear?!? or is a gear just a wheel and axle with little levers on it?)
How many simple machines on a tricycle anyway?