Simple Machines

Susan Frazier                  Fort Dearborn
                               9025 Throop Street
                               Chicago, Ill.
                               312-881-5180

Objectives:

Adaptable to grades 1 to 12

The student will be able to:
      
      1) define and give examples of "work" and "machine"
      2) identify simple machines (inclined plane, screw, lever,
         wheel and axle, wedge, and pulley)
      3) classify simple and compound machines 
      4) name body parts that can be used as simple machines

Materials: 

paint can, book, spring scale, meter stick, string, milk carton, several 
pulleys, toy car--weighted, three boards-same length, three boards-different 
length, long pole

Strategy:

                            Work and Simple Machines

     Have several students attempt to open an empty paint can with their hands 
or attempt to move a heavy desk.  Have the students determine that although   
force was used, the objects did not move a distance and there was no motion; 
thus, no work was done since work is equal to force times distance. 
     Then have a student open the paint can by using something to pry off the 
top of the can.  Explain that the object was used as a lever, one kind of 
simple machine, and that a machine is something that makes work easier to do.
Also help the students discover that two or more simple machines can be used 
together to make compound machines. 

                                 Activity-Lever

     Tie a book to one end of a meter stick.  Use a milk carton weighted with 
dirt or sand as the fulcrum, the point on which the stick rests or turns.  Set 
the fulcrum at the 15 cm mark.  On a chart, record where the fulcrum was set, 
the load arm length, and the force arm length.  Use the end of the spring scale 
to pull down the end of the meter stick and record the force shown on the scale. 
Repeat the steps above for 20 cm, 25 cm, 30 cm, and 35 cm.  Discuss the 
placement of the fulcrum in relation to the placement of the load and the amount 
of force needed to lift the load.  Have the children discover the direction the 
load moves and the direction of the force. 

                                 Activity-Pulley
 
     Use a horizontal bar to attach a fixed pulley, a combination of a fixed 
pulley and movable pulley, and a combination of several fixed and movable 
pulleys.  Lift a load attached to a spring scale straight up in the air.   Next, 
lift a load attached to a fixed pulley, then a fixed and movable pulley, and 
finally, a multiple pulley combination.  Record the force needed for each.  
Discuss which one required the most force to lift the load.  Which one required 
the least force.  Determine the direction of the load and the force for each 
kind of pulley.  Determine the relationship of the number of pulleys used and 
the amount of force needed to lift the load. 
 
                      Activity-Inclined Plane, Screw, Wedge

     Discuss the relationship of the inclined plane, the wedge, and the screw.  
Next, attach a car to a spring scale and lift up in the air.  Then, pull a car 
attached to the spring scale up three different inclines--the same length, but
different heights.  Pull a car up three different inclines with different 
lengths but raised to the same height.  Record the force for each.  Notice the 
relationship of the length and height of the inclined plane and the amount of 
force used.

                             Activity-Wheel and Axle

      One person holds a stick with one hand while a partner places her/his 
hands on either side of the person holding the stick.  The partner tries to   
turn the stick "wheel" while the person holding the middle tries to keep the
stick from turning.  Next, the partner moves her/his hands farther apart and 
tries to turn the wheel.  The partner continues to move the hands apart 
until the wheel turns easily.  The person's arm acts as the axle, and the pole 
is the wheel.  The children determine the relationship between the size of the 
wheel and the amount of force needed to turn the wheel.


                              Activity-Culminating

Name body parts used as machines.  Rapidly classify machines placed in a brown
bag.  Use as a team game.