Leon Foucault experimented with a long, heavy pendulum to see if the movement of the Earth was observable to the naked eye. Purchase a pendulum system for students to observe or build one. You'll need a heavily weighted pendulum with a protruding end (a weighted, pointed Christmas ornament may do) and a long, heavy cord. Clean, fine sandbox sand under the pendulum can track how the swinging pendulum slowly turns. For an advanced twist, pair up on a webcam with a classroom at a very different latitude to see the difference in how the pendulums mark the sand.
The lever, like other simple machines, was not invented so much as discovered by different individuals at different times and places in history. The pulley; the inclined plane; the wheel and axle; the wedge, and the screw all lend themselves to classroom experimentation. The Greek Archimedes, however, is known for his calculations using the lever. He famously said, "Give me a place to stand and with a lever I will move the whole world." Use Archimedes' premise and a playground seesaw or other simple lever to move ever larger loads using different placement of the fulcrum and different lengths of the lever.
Find or build a "Newton's cradle." Evenly weighted and spaced balls must be hung freely from a frame in a row. When a ball at one end is swung against the others, the ball on the far side will swing out nearly as far in the other direction. If two balls are swung, two corresponding balls will swing out on the other side. This toy demonstrates Newton's law of conservation of momentum.
Newton's laws of inertia can be applied to the use of simple centripetal motion devices. Try spinning a penny inside a large balloon inflated to about 80 percent capacity. The penny should circle the inside of the balloon like a race car edging up the curve of a track. Stop moving the balloon and rest it between your hands, and watch the movement of the penny continue after you stop adding energy to the system. Use a hanger and penny to conduct a similar experiment. Stretch the wire hanger into a diamond shape and balance the penny on the hooked end while swinging the hanger by the far end. The penny should rest on the end of the hook as if it were glued there while you swing the hanger in wider and wider arcs. Coordinated students may be able to swing the hanger entirely in a circle without losing the penny. This demonstrates an object's tendency to continue moving in a straight line and the power of centripetal force.