Buy or borrow five identical candles. Tie four of the candles together in a bundle. At night, find a relatively dark location. Light all five candles and wait for the candles to start burning evenly. Have one member of your group take the single candle and walk ten paces away. Have another group member take the bundle of four candles and walk away in the same direction until the rest of the group judges that the four candles together appear as bright to them as the single, closer candle. Measure how many paces the four candles are from the group. Find the ratio of the distances of the four candles and the single candle and compare the result to what you would expect on the basis of Equation 6.1.
Go to an asphalt parking lot early in the morning. Have one-half of the group stand on one side of the parking lot and the other half on the other side. Have the two groups observe how steady the other group appears to be when viewed across the parking lot. Repeat the experiment after the Sun has been shining on the dark parking lot for much of the day. Get the entire group together to discuss why the shimmering due to the parking lot is different at the two times of day.