How Your Eyes See

What You'll Learn

Reflexes are automatic responses that happen without conscious thought. When you touch something hot, your hand pulls away before your brain even registers the pain.

Key Words

organ
skeleton
muscle

Materials Needed

cotton balls
cups
different scented items
textured objects

Safety First

Adult supervision recommended.

Steps

Step 1 — Read

Look at the vocabulary words and write a definition for each in your own words.

Step 2 — Do

Test reaction time: have a partner drop a ruler and catch it. Record the centimeter mark 10 times. Calculate your average reaction time.

Step 3 — Observe

Watch carefully for any changes and note the time.

Step 4 — Record

Create a data table to organize your measurements.

Check Your Understanding

Question 1

1 of 3

What is the largest organ of the human body?