Here's what you'll need: • a 30 cm (12 inch) plastic or wooden ruler • 10 pennies (All pennies should be newer than 1990. Can you figure out why?) • a pencil • a level desk or table top

Here's what to do:  
1. Lay down the pencil flat on the desk.  
2. Lay the ruler across the pencil so that the two ends of the ruler teeter back and forth like a see saw.  
3. Adjust the ruler on the pencil so that the two ends balance perfectly. The balance point should be at about the 15 cm (6 inch) mark.  
4. Stack 5 pennies at the very edge of the ruler on the 1 cm (1 in.) side and the other 5 pennies on the very edge of the 30 cm (12 inch) side. Since the two piles of pennies are about equal in weight, the two ends of the ruler should remain balanced.  
5. Take three pennies off of the 30 cm (12 inch) side and place them on the stack at the 1 cm (1 inch) side. You should now have 8 pennies on one side and 2 on the other. The ruler should be tilted down toward the 1 cm (1 inch) side. You've just constructed a lever!  
How can you lift four times your weight? Try it with these pennies! Without adding any weight to either side and without moving the pennies, can you figure out how to get the two ends of the ruler to balance? (Note: The ruler doesn't have to balance exactly — it just needs to be at the point where it teeters back and forth without touching the desk.)
Before you try this Science Lab, predict what will happen with your classmates. When you've finished the Science Lab, share your results with the rest of the class.
