• 4-6
• K-3

• To learn about first, second and third class levers.
• To learn lever vocabulary.

• Plastic spoons
• LEGOs (or another building material; e.g. cardboard, straws, popsicle sticks etc.)
• Rubber bands
• Cotton balls
• Tape
• Ruler - to measure distance of cotton balls

• Put kits together for each group. Each kit should contain:
• One spoon
• Three cotton balls
• Three rubber bands
• Plenty of LEGOs or other building material.
• Have enough tape in the front of the room for all groups.
• Arrange students into groups
• Distribute materials.
  

There are three classes of levers:

    First Class Levers:

• Have a fulcrum in the middle, the effort on one end, and the load at the other end.
• Example: see-saws.

    Second Class Levers:

• Have the fulcrum at one end, the effort at the opposite end and the load in
  the middle.
• Example: wheelbarrow

     Third Class Levers:

• Have the fulcrum at one end, the effort in the middle and the load at the
  opposite end.
• Example: tweezers 

• Lever - a simple machine that eases the effort needed to lift a load. 
• first class levers
• second class levers
• third class levers
• fulcrum - Center of a lever which the lever rotates around.
• effort - The amount of force needed to work a lever.
  
• load - The object that needs to be lifted or moved by a lever.
  

1. Review the concept of levers with the class. Be sure to explain the different classes
   of levers. The powerpoint document attached is very useful in explaining the
   concept of levers.
2. Explain the activity challenge
1. Ask students if they know what a catapult is and what they have been
   historically used for.
2. Explain that a catapult is a type of lever - this is why people used catapults;
   to launch heavy loads at other people during middle age wars before gun
   powder could do it.
3. Have the students construct a lever using a LEGO (or other materia) base, using
   the spoon as the lever, and the rubber bands as the driving force. Allow students
   to be creative and place the fulcrum, load and effort in different places for different
   results. Students can also use their hands to pull on the catapult.
4. When the students have completed their levers, gather the class together to test
   and discuss the activity.
1. Let each group demonstrate their catapult and measure the distance that
   their cotton ball is launched from a starting point.
1. Let each group try their catapult three times and record the best score.
2. When all the students have tested their designs discuss the results
1. Which catapult threw the ball the farthest and why?
2. What class of catapult was the winning design?
3. How was this design different from other designs?
4. Let student compare the different designs and the test results.
   

• Build all three classes of levers. Students can use some type of weight
  (pennies, etc.) as a driving force like a trebuchet.