Place a 12-inch ruler on the end of a flat workstation, such as a table or desk. The workstation should have an open area under it so your pendulum is not obstructed when it swings. The end of the ruler should stick out 4 inches from the end of the workstation.

Place a heavy book or bag of sugar on top of the ruler to hold it in place.

Mark a 3 1/2-foot piece of string at 19 1/2 inches, 27 inches and 35 1/2 inches with a marker. Tie the string to the end of your ruler. Most rulers have a hole in one end, so use this. If yours does not, tie the string around the ruler.

Tie the loose end of the string to a 3 1/2 oz. weight. You can use anything you would like for the weight, as long as it is 3 1/2 oz. and can be tied to the string.

Make a note of the length of the string from the knot at the ruler to the weight. Pull the weight to the side and let go of it. Allow it to make 10 full swings.

Observe the speed and height of the swings. Record your results on a piece of paper.

Shorten the string to the 35 1/2 inches mark you made and repeat Steps 5 and 6.

Repeat Step 7 with the 27 inches and 19 1/2-inch measurements.

Write a report discussing what a pendulum is and how it works. Also discuss your results with the different lengths.