Reacting quickly

Reaction time is the time between a signal and your response. We can measure it with a stick. A grown-up supervises. Sit at a table with your arm resting on the edge. A partner holds a metre stick at the top so that the zero end hangs between your open thumb and finger, not touching. The partner lets go without warning, and you catch it. The number where your finger stops is how far it fell, and a longer fall means a slower reaction. The chart turns distance into time. Do three tries and find the average: add the three times and divide by three. Then change one thing, the signal: close your eyes and catch when your partner says “now”. Keep everything else the same. Compare the averages. Never throw the stick, and keep it away from faces.