A Science Experiment With Reflexes for Kids

Reflexes are involuntary responses that help your body function.

Reflexes make up an important part of human reaction. They help you rebalance when you stumble and catch yourself when you fall. Reflexes cause you to pull your hands back from hot surfaces and jump out of the way of falling objects. The faster your reflexes, the better you avoid danger. Help your students understand how reflexes work with some classroom science activities.

Pupillary Reflexes

Your pupils have reflexes just like the rest of the muscles in your body. They react to light changes to protect your eyes from too much light and open to help you see in the dark. Demonstrate this by pairing each student with a partner. One partner must close his eyes for 10 seconds and then open them quickly. The other partner should observe his pupils change from large to small. The other partner then closes her eyes so the first partner can observe the same response.

Automatic Reflexes

This experiment shows how people react to sudden environmental changes, especially changes that may signal "danger." One student must be in on the experiment for it to work. At a pre-determined time, this student should slam a hardback book to the floor as hard as she can. She must then observe the reactions of her fellow students. Modify this experiment by doing other things in the classroom as well. Turn off the lights suddenly, snap open a window shade or toss a paper ball in the air over the students' heads.

Kicking Legs

Many children have had doctors test their reflexes with a small, light mallet tap to the knee. Recreate this experience with students in pairs. One student in each pair should tap his partner on the knee with a finger to see if he can find the reactive part of the knee. The students may then switch. Modify this by adding a stopwatch to see who reacts the fastest. Sharp taps with fingers should do the trick. Students should never hit each other with a tool or implement; this could cause serious injury.

Catch It if You Can

Students split off into pairs for this activity to see who has the fastest reaction time. One student in each pair holds a ruler, yardstick, pen, or piece of chalk by one end. The second student holds her hands about 1/8 inch on either side of the object, without touching it. The first student drops the object without warning and the second student must bring her hands together to catch it. The first student times his partner's response time with a stopwatch. Each student should have a chance to catch the object five times. Arrange the information to see who's the fastest: boys v. girls, athletes v. non-athletes, musicians v. non-musicians and athletes v. musicians.

References

• Washington: Reflexes
• Education: Lightning Fast Reflexes