Integrated Science
Name _____________________________
Three Classes of Levers Lab
Background All levers have an effort arm, load arm, and a fulcrum. The relative positions of
these three parts determines the class of lever.
Materials: 2 meter sticks
string
weights
tape
bottle
Wood blocks
Procedure
First Class Lever
1. Make a lever using a long board and short block for a fulcrum. Position the fulcrum
under the center of the long board.
2. Have two students stand on either end of the long board. What happens?
3. How would you change the positions of the students to balance the board if one student
was very small and one was much larger? Draw or describe below.
4. Draw the positions of the load, effort and fulcrum in a first class lever.
Second Class Lever
1. Cut about a 1 meter length of string and tie one end around a wood block. Hold the free
end of the string and lift the block about 15 cm above the floor.
2. Tape one end of a meter stick to a table edge so
that the majority of the meter stick hangs over the
edge parallel to the floor.
3. Tie the free end of the string to the meter stick so
that the block is hanging down from about the
center of the meter stick.
4. Lift the free end of the meter stick until the block is again about 15 cm above the floor.
Compare the effort it takes to lift the block using the string (step 1) and using the meter
stick (step 3). Which seems easier? Write your observations.
5. Change the position of the load (block) on the meter stick. Move it closer to the table.
Lift the block. How does this feel now? Is it easier or harder?
6. Move the load (block) closer to your hand. How does this feel? Is it easier or harder?
7. Draw the positions of the load, effort and fulcrum in a second class lever.
Third Class Lever
1. Cut a piece of string about 1 meter long. Tie one end to the end of a meter stick, and the
other end to a roll of tape.
2. Stand a soda bottle on the floor. Hold one hand on the
bottom of the stick and the other hand directly above the
other hand. Keep both hands at the far end of the meter
stick.
3. Try to hook the ring of the tape over the bottle moving the
meter stick with the hand on top only.
4. Rate how difficult this is, 1 to 5, with 5 the hardest. ____
5. Move your hands closer to the string. Try again. Rate this position 1 to 5. ____
6. How does the position of your hands effect the degree of difficulty?
Another Example
7. Construct giant “pinchers” by taping the ends of two meter sticks together.
8. Hold the sticks, one in each hand, about 50 cm from the free ends.
9. Try to pick up a “load” off your desk (a notebook, bottle, etc). Try to carry it to a
neighboring desk.
10. Is this work harder to do with or without the “machine” lever? WHAT COULD YOU
DO TO MAKE IT EASIER (and still use the pinchers!)?
11. Draw the positions of the load, effort and fulcrum in a third class lever.
Questions
Classify the following as first, second or third class levers by writing 1, 2 or 3 next to each.