Pour sand around a pendulum’s base. Most pendulums hang a few inches above their base; fill the base with a couple of inches of sand so the pendulum point glides gently over the sand. Smooth the sand so that the pendulum makes visible designs on it. Make a small dot at the pendulum’s equilibrium position -- where the pendulum hangs when undisturbed. Pull the pendulum back and let it go. Watch as it marks its oscillation patterns in the sand. Measure the amplitude by measuring the distance from the point of equilibrium to the top of the oscillation.
Measure the time of an oscillating tetherball attached to a pole. Tetherball poles are common toys in school parks; they consist of a ball attached to a string hanging from a tall pole. Using a stopwatch, find out how long it takes for the ball to repeat its oscillation; for example, note the time when the ball passes its point of equilibrium and when it returns. See who can swing the ball the highest, which will result in a slower oscillation period since the ball will take longer to repeat oscillation.
Watch a toy drinking bird as it oscillates back and forth, taking "drinks" of water each time. Using a stopwatch, count how many drinks the bird takes in a second and determine the frequency. For example, a bird that drinks every half-second will have a frequency of two drinks per second.
Set two pendulums beside each other. Start the pendulums at the same time with the same amount of force. Watch as the pendulums are "in phase" -- when they seem to move in sync -- and when they are "out of phase" -- when they move in opposite directions from each other. While phase is the measurement between two different oscillations in the same system, setting two pendulums beside each other is an easier way to represent the term.