Place the large pan firmly on a table. Make sure the table is near an outlet and is big enough for the dish pan and the fan.
Tape the ruler inside one end of the pan. Make sure the "0" of the ruler is down.
Use the gallon jug to fill the pan with water. Fill the pan until the water level reaches 4 inches deep.
Place the fan on the opposite end of the pan from the ruler, aiming the fan down toward the surface of the water.
Turn the fan on low. Record the effects that the low fan speed has on the surface of the water.
Increase the fan speed to medium and then high, recording your results at each speed.