Simple Machines

Bonnie Anderson                Libby School Annex
                               5338 S. Loomis
                               Chicago IL 60609
                               (312) 535-9350

Objectives:

This lesson was designed for students in grades 2-4.
The students will be able to identify the six simple machines and how they are 
used in our lives.  They will gain a basic understanding of the use of force and 
effort. 

Materials Needed:

For Inclined Plane - Weights (identical for each group), Spring scales, Ramps 
(cardboard, approximately 5"x30")

For Wedge - Child's ax, "Blocks" of cardboard (use masking tape to tape together 
8 4" squares of cardboard to form a block, simulating a wood block), 2" bolts 
with hex heads, 2" nails with large heads, Pencils, Hand-held pencil sharpeners, 
Iced oatmeal cookies, Oranges, Plastic knives 

For Screw - Pencils, Paper triangle shapes (8" long), 2" screws, "Blocks" of 
cardboard 

For Lever - 3 stuffed teddy bears (2 the same size and 1 much larger), Cement 
block or wood block , Tongue depressors, Pencils, Sugar cubes or mini-
marshmallows, Child's toys (rakes, shovels, hoes, wheelbarrow, broom, Nerf Bat, 
Nerf Football, canoe and oar) 

For Wheel and Axle - Small child's bike (just the front wheel and handlebars 
will do), Large teddy bear, Large photos of Ferris Wheel, Merry-Go-Round 
(child's toys work very well), Screwdrivers,  2" screws, "Blocks" of cardboard 

For Pulley - Small Kermit the Frog doll, Flagpole about 3' high with fixed 
pulley and flag, Gallows-type contraption with fixed pulley at top, movable 
pulley suspending weight at bottom, Spring scale, Snow White doll, Model of 
well with fixed pulley

Strategy:

Inclined Plane - Draw 2 identical houses on board, except one house has a ramp 
to get to the door, and the other has stairs.  Discuss the houses, and have the 
children tell you that the house with the ramp probably has a person in a 
wheelchair living there.  Discuss whether it is easier to lift that person 
straight up to the door or to use the ramp.  Use the cardboard ramps to 
demonstrate the wheelchair ramp in the house.  Measure the effort that you need 
to lift a weight straight up to the height of 12", then measure the effort that 
you need to pull the same weight up the ramp.  Determine which method required 
less effort.  (Be sure to clarify the word plane as a multi-meaning word, since 
we are not referring to an airplane.)  Elicit from the children other examples 
they may have seen of inclined planes. 
 
Wedge - Display the child's ax and reference it to the tools the settlers and 
Indians used in "Pocahontas" or the woodcutter's ax in "Little Red Riding Hood".  
Help the children to describe the ax as being a triangle or a wedge shape.  

Distribute a cardboard block, bolt, and nail to each group.  Ask the children 
to compare the bottom of the bolt and the nail, then to compare the effort 
required to push each into the block.

Distribute a pencil to each child.  Ask them to sharpen the pencils without any 
help.  Distribute the sharpeners, have the children observe the edge of the 
sharpener is a very sharp wedge, then allow them to use the sharpeners to 
sharpen the pencils.  Elicit from the children other examples of wedges they may 
have seen. 

Distribute a plastic knife and either an iced oatmeal cookie or an orange to 
each student.  Ask them to pretend they are very young and have no teeth, so 
they will have to keep their lips curled around their teeth.  Then have them try 
to eat their cookie or orange without using teeth or fingernails.  Have them 
look at their knife and determine that the knife is a wedge they can use to peel 
the orange or cut the cookie.  Finally, have the students feel their teeth and 
determine that they are sharp and also function as a wedge they can use to cut 
the cookie or peel the orange. 

Screw - Ask the children to wind the paper triangle around their pencil (so 
that it looks like a screw).  Compare the screw to the nail and the bolt and 
then ask the children to use their fingers to put the screw into the cardboard 
block.  The children should be able to recognize that a screw is actually an 
inclined plane wound around.  Elicit from the children places that they have 
seen screws used, such as drills, etc. 

Lever - Set up a see-saw with a board and a cement block.  Have the two small 
teddy bears "play" on the see-saw, then have the large bear come to "play".  
When he jumps on one side of the see-saw, one of the small bears will fly off.  
Ask the children why this happened and they should indicate that the large bear 
was too big and/or he ran and jumped with too much force.  Define the see-saw as 
a lever, and point out that a lever has to have 3 components - a fulcrum, a 
load, and a force.  

Distribute a tongue depressor, pencil, and several sugar cubes or mini-
marshmallows to each child.  Have the children make their own see-saws.  They 
may experiment with moving the fulcrum (pencil) and the amount of force which 
they apply to the load. 

Ask for volunteers to come forward to demonstrate how "Old McDonald" used tools 
like shovels, hoes, rakes, wheelbarrows.  (Sing "Old McDonald".)  Ask for a 
volunteer to demonstrate the use of a broom.  Ask for a volunteer to demonstrate 
use of the bat and ball.  (Sing "Take Me Out to the Ball Game.)  Ask for a 
volunteer to demonstrate use of the football.  (Sing "Bear Down Chicago Bears".)  
Display the toy canoe and oar and demonstrate their use.  The children should be 
able to indicate that all of the toys from this demonstration are examples of 
levers. 

Wheel and Axle - Display the front wheel and pedals from a child's tricycle.  
Help the teddy bear ride the bike.  Demonstrate how the pedals (axle) turn the 
wheel so that the wheel can travel a great distance.  Explain how a ferris wheel 
and a merry-go-round function as wheels and axles. 

Distribute the screwdrivers, screws, and cardboard blocks.  Have the children 
use their screwdriver to put the screw into the cardboard block.  Explain that a 
screwdriver is a wheel and axle, with the wheel turning the axle and increasing 
the force applied.  Try to elicit from the children the understanding that a 
doorknob is another example of a wheel and axle. 

Pulley - Display the flagpole and tell the children that Kermit has a job to do 
- raise the flag!  His problem is that he cannot jump to the top of the flagpole 
to pull the flag up.  He finally tries pulling on the rope, which will raise the 
flag.  Have the children observe that Kermit pulled down, but the flag went up, 
so a "fixed" pulley changes the direction of force.  (Be sure to clarify for the 
children that "fixed" is a multi-meaning word, meaning stationary, not the 
opposite of broken.) 

Use the gallows contraption to illustrate the use of a movable pulley.  
Determine the force necessary to raise a wooden block, then compare that to the 
force necessary to raise the block using the movable pulley.  The children will 
be able to see that a movable pulley reduces effort. 

Stand Snow White at the well.  Tell the children that Snow White has to work 
very hard for the wicked Queen.  One of her jobs is to bring water from the well 
every day.  Demonstrate that Snow White uses a pulley to help her bring up 
water. 

Performance Assessment:  

In each example of a simple machine, the children should be able to explain how 
the machine helped to reduce effort, increase force, or change the direction of 
force.  They should be able to give several examples of simple machines they see 
and use every day.