Marvelous, Simple Machines
for 7th grade
Activity Guide
• Challenge: Discuss (10 minutes)
• Generate Ideas and Multiple Perspectives (instructor choice)
• Research and Revise (and Test Your Mettle)
– Activity 1: rotate through stations (25-30 minutes)
• In groups of 4 or 5, students rotate to each of the six simple machine
stations to conduct tests.
• Students record data in “Testing Simple Machines” worksheet
– Activity 2: Review (10 – 15 minutes)
• Discuss/compare “Testing Simple Machines” worksheet as a class
• Look at images of real-life simple machines and discuss each
– Activity 3: (25-30 minutes)
• Complete “Testing Simple Machines” worksheet
– convert grams to Newton’s in chart
– convert metric units in the “Challenge” to English units
• Go Public: (instructor choice)
– Revisit the Challenge
– Design a solution and communicate it in writing with sketches
Teacher tips
• It helps to set up the simple machines and use them before class.
• Set up each simple machines on a separate table.
• Groups of 4-6 students will rotate to each table to use/test each simple
machine and record their data.
• It is beneficial to discuss that a simple machine does not reduce work, it
typically makes it ergonomically easier. It the force needed to move an
object is reduced, then the distance to move it typically increases (look at
an inclined plane for an example –distance is how far the object moves on
the plane, not the height it ascends)
• The larger simple machines – lever, pulley and inclined plane are stored in
the equipment room on the right near the door.
• The lever, Hall’s cart, wheel and axle, cart without wheels, and pulley
already have string attached. If this string is not present, you have an extra
spool, along with a pair of scissors, in the storage cart for 7th grade. You
may ignore the directions to attach the string if it is already attached.
Teacher Prep
• Assemble materials listed on next page
• Set up stations
– Each simple machine will be set up on a different table
resulting in 6 stations, 1 for each simple machine
– Use the materials guide on the next page to set up
your stations
– Each group of 3-5 students receives 1 copy of “Testing
Simple Machines” chart to complete.
• Students will rotate to each of the simple
machine stations to make their observations –
spending about 4-5 minutes at each station
Materials
• Lever*
• Screw
– Lever
– 1 spring scale
– 1 200 mg weight
• Incline Plane*
– 1 wooden block with bolt
– 1 hex-head driver
– 1 ruler with English units
• Wedge
– Incline plane
– Hall’s cart
– 1 spring scale
• Pulley*
–
–
–
–
Pulley stand with 2 pulleys attached •
1 extra pulley
2 spring scales
•
1 200 gram weight with hook
• Wheel and axle
–
–
–
–
– 1 wedge
– 1 block of wood with bungees
attached
– 1 rubber mallet
1 wooden car with wheels
1 wooden car without wheels
1 spring scale
1 200 gram weight with hook
6 copies of “Testing Simple Machines”
in mechanical room filing drawer on
bottom left
Pens/pencils
*These larger pieces are stored in the
equipment room to the right as you walk
in. They are bungeed in place, please
return them to this location when you
have completed the lab. Thank you!
Location of all Materials
Drawer 3b1:
• 28 mechanical pencils
• 1 spool parachute cord
• 1 pair scissors
• 1 ruler
• 2 metric measuring tapes
• 5 200 gram aluminum weights
Drawer 3b3:
• 6 spring scales
Drawer 3b4:
• 1 blue Hall’s cart
• 1 wooden wheel & axle
• 1 wooden car without wheels
• 1 wedge stand wrapped with bungees
• 1 wooden wedge
• 1 block with hex bolt inserted
• 1 hex head driver
In equipment room on left
• 1 incline plane
• 1 lever
• 1 pulley stand with pulleys and string
Challenge
You are a mechanical engineering consultant. Your client has
asked you to design a conveyor belt from simple machines that
will move a 40 kg box directly from the loading dock door to a
counter in another room.
5 M wide
Box
3 M wide wall
• The box is 1 meter tall x 0.75 meters wide x 1.5 meters long
• The box must be moved across a 5 meter x 9 meter room and up
on top of a counter that is 1 meter from the floor, 0.5 meters wide
and 3 meters long.
Counter
10 3 M long
wall
9 M long
Guiding Question
• What is a simple machine?
– Name the six simple machines
– What do they do? How do they work?
– Identify real-world examples of simple machines
• What is work?
– Do simple machines reduce the total amount of
work required to do an activity?
– Explain your answer.
Worksheet
Activity 1
• Activity 1: rotate through stations
– In groups of 4 or 5, students rotate to each of the
six simple machine stations to conduct tests.
– Students record data in “Testing Simple Machines”
worksheet
(25-30 minutes)
Lever
Fulcrum
Hang 200 gram mass on end of lever.
Hang spring scale on opposite end of lever.
• Pull spring scale until
lever is level.
• Record the “effort”
that the spring scale
indicates in units of
grams in your Testing
Simple Machines
Chart.
Now move mass to hole nearest lever stand.
Pull the spring scale to level the lever. Record
“effort” from spring scale.
• Note that we decreased the
distance of the mass from
the fulcrum (point where
the lever attaches to the
support).
• How will this affect the
force needed to raise the
weight of the mass?
• What could you do to make
it harder (use more force) to
raise the weight?
Remove the mass and scale from lever.
• Return the materials to the places that you
found them.
Incline Plane
Set up cart
• Set 200 gram mass on the Hall’s cart.
Raise the incline plane to the 9th hole
from the bottom. Secure with pin.
Place Hall’s cart at bottom of incline plane.
Pull the string up and over pulley.
Make sure incline plane is at the edge of the table and the string
dangles from the pulley off the edge of the table.
Attach a spring scale to the loop in end of
the string hanging off the table.
Pull the spring scale down toward the floor to pull the cart up the plane.
Record the “effort” in grams registered on the spring scale in your
Testing Simple Machines chart.
•
Pull the cart up the
incline by pulling down
on the scale attached to
the string.
• Record the “effort” that the
spring scale registers while
you are pulling on the cart.
Record in grams in the
“Testing Simple Machines
Chart.”
Raise the incline plane to the 18th hole
from the bottom. Secure with pin.
• Note that we are doubling the
angle of the incline plane.
• How will this affect the
“effort” force needed to pull
the Hall’s cart up?
Place Hall’s cart at bottom of incline plane
with string pulled up plane and over pulley.
Make sure incline plane is at
the edge of the table and the
string dangles from the pulley
off the edge of the table.
Attach a spring scale to the end of the
string hanging off the table.
• Pull the spring scale down
toward the floor to pull the
cart up the plane.
• Record the “effort” registered
on the spring scale in grams in
your Testing Simple Machines
Chart.
Remove weight from cart.
• Return the materials to their original location
on the table.
Pulley
Hang a 200 gram mass from one of the
loops on the single pulley. (The pulley
with the string pulled through it.)
Be sure to hold onto the
other side of the string
when you are hanging the
weight.
Hang a spring scale from the other loop.
Pull the spring scale down until you see how
much “effort” force is needed to lift the mass.
Record the “effort” from the
spring scale in units of grams that
is needed to lift the weight of the
mass in your “Testing Simple
Machines Data Chart.”
Return the materials to their
original location on the table. You
are ready for the double pulley.
Set up the double pulley system.
• Use the right side of the
pulley stand.
• Allowing the pulley to
hang down from to the
left, pull the loose end
of the string up and
through the pulley from
the right to the left.
Thread end of string up to the top pulley
(the one where the string is secured).
• Making sure to hold
onto the looped, free
end of the string,
hang a 200 gram
mass from the pulley.
• Pull the looped end of
the string down and
hang a spring scale
that measures units
of gram from it.
Pull down on the spring scale and take
a reading from the spring scale
• Read the “effort” that is needed
to lift the 200 gram mass.
• Record this in your Testing
Simple Machines Chart.
Tip: make sure the
pulley does NOT get
stuck on the bolt in
the pulley stand.
Remove spring scale, mass, and pulley.
Return the materials to their
original location on the
table. You are ready to
move on to the next station.
Wheel and Axle
Set the 200 gram mass on the car
without wheels
Pull the car without the wheels across
your table with the spring scale.
• Record the “effort” measured in grams from
the spring scale that is required to move the
cart in your “Simple Machines Data Chart.”
Place the 200 gram mass on the car
with wheels.
Use the spring scale to pull the car with
wheels across your table.
• Record the “effort” force required to pull the
car in your “Simple Machines Data Chart.”
• How does this force compare to the force
required in the car without wheels?
Remove weight and spring scale.
• Return materials to their original place on the
table.
Screw
Put the bolt in the block of wood. Screw it in
so that it is 1-inch from the top of the block.
Put the hex-head driver on the bolt.
• Line up the line on the block with the line on
the top of the hex-head driver.
Use the ratchet to screw in the bolt.
• Count how many turns it takes to screw the
bolt in 1-inch. Record in your “Simple
Machines Data Chart.”
• How could this make work easier. Name a
practical example.
Return materials to their original
location on the table.
Wedge
Use the handles to try to pull apart the
blocks of wood.
Record the effort that you expended to pull the blocks of wood apart in your
Testing Simple Machines chart.
Put the wedge at the indented slot
between the two blocks of wood.
Use the rubber mallet to hammer the
wedge between the two blocks of wood.
• How much force did you
use?
• How did this compare to
trying to pull the wood
apart?
• Record your findings in
your “Simple machines
Data Chart.”
Tip: KEEP fingers AWAY from
the space between the blocks
of wood!!!! It will PINCH.
Carefully remove wedge from block of
wood by tilting the wedge to the side
and pulling it up and out.
Return materials to original location.
Activity 2
• Discuss/compare “Testing Simple Machines”
worksheet as a class
• Look at images of real-life simple machines
and discuss each
(10-15 minutes)
Which type of simple machine is this?
• How does it work?
What type of simple machine is this?
• How does it work?
What type of simple machine is this?
• How does it work?
What type of simple machine is this.
How does it work.
What type of simple machine is this?
• How does it work?
What type of simple machine is this?
How does it work?
Activity 3: Calculations (25-30 minutes)
• Complete “Testing Simple Machines” worksheet
– convert grams (g) to Newtons (N) in chart
• We measured mass units from the spring scale and now we
need to calculate the force applied, the “effort,” by using
Newton’s 2nd Law, Force = Mass x Acceleration
• These measurements were taken in an earth setting where
the acceleration acting on a mass in the vertical direction is
due to earth’s gravity, taken at sea level to be 9.81 m/s2
• Convert the metric units in the “Challenge” to
English units, meters => feet
– Always good to know unit conversions, and what a
great way to reinforce math with ratios!
• 2.54 cm = 1 inch
100 cm = 1 m
12 inches = 1 foot
Go Public – Revisit Challenge
You are a mechanical engineering consultant. Your client has
asked you to design a conveyor belt from simple machines that
will move a 40 kg box directly from the loading dock door to a
counter in another room.
5 M wide
Box
3 M wide wall
• The box is 1 meter tall x 0.75 meters wide x 1.5 meters long
• The box must be moved across a 5 meter x 9 meter room and up
on top of a counter that is 1 meter from the floor, 0.5 meters wide
and 3 meters long.
Counter
10 3 M long
wall
9 M long
Vocabulary
• Simple machine - requires application of only one force to work
• Force – the amount of effort necessary to do work; usually
measured in pounds (lbf) or Newtons (N)
• Lever
– The fulcrum is the pivot point about which the lever rotates or turns.
•
•
•
•
•
•
Pulley
Inclined plane
Wheel and axle
Screw
Wedge
Work = force x distance; the amount of force needed to move an
object a given distance
Simple Machines
Simple Machine
How does it work?
Real world example(s)
Lever
A lever is a stiff rod that rotates around a pivot point. Downward
motion at one end results in upward motion at the other end.
Depending on where the pivot point is located, a lever can
multiply either the force applied or the distance over which the
force is applied.
Teeter totter, scissors, crowbar,
toilet flusher, clippers, stapler,
bottle opener…
Inclined Plane
An inclined plane is a slanting surface connecting a lower level to
a higher level. The longer the inclined plane, the less force
required, but greater distance required to move a load. Shorter
planes = more force, but less distance.
Roller coaster, dump truck, stairs,
parking ramp, wheel chair ramp
…
Pulley
A pulley is a rope wrapped around a grooved wheel. A single
pulley simply reverses the direction of a force. When two or more
pulleys are connected together, they permit a heavy load to be
lifted with less force. The trade-off is that the length of the rope
must move a greater distance than the load.
Rock climber pulleys, clothesline
pulley, flag pole pulley, drapery or
shade pulleys…
Wheel and Axle
In this machine a wheel or spoke is locked to a central axle so that
when one is turned the other must turn. A longer motion at the
edge of the wheel is converted to a shorter more powerful
motion at the axle. In reverse, a short powerful force at the axle
will move the wheel's edge a greater distance.
Door knob, bicycle, roller skates,
windmill, fan …
Screw
A screw is a central core with a thread or groove wrapped around
it to form a helix. While turning, a screw converts a rotary motion
into a forward or backward motion (linear motion).
Jar or bottle lid, cork screw, piano
stool, drills, screws …
Wedge
A wedge is two inclined planes back to back forced into a solid
object. A wedge converts motion in one direction into a splitting
motion that acts at right angles to the blade.
Chisels, sledge hammer, car tire
wedge,