Battery powered, portable and light weight, this digital timer measures reaction speeds to hundredths of a second. The selector switch can be set to send stimuli as light, sound, or touch. Students activate a switch in response to the stimulus received and the LED display clearly shows their reaction time. Experiment with and discuss the effects of fatigue, stimulants, depressants and general fitness (athlete vs. non-athlete). Students will also be able to determine if any one type of stimulus consistently provokes the fastest response. Supplied with a teacher's guide, the Reaction Timer requires four AA batteries, not included.