Lesson Plan: Simple Machines
Title: Rapunsel and the Pulley
Cross-Curricular Subject: Language Arts, Science, Math
A7 read and represent decimals to thousandths
A9 compare and order decimals
B1 find sums and differences involving decimals to thousandths
B5 find simple products of whole number and decimals
C5 recognize and explain how a change in one factor affects a product or quotient
F1 use double bar graphs to display data
Initiating and Planning
Propose questions to investigate a practical problems to solve
State a prediction and hypothesis based on an observed pattern of events
Identify and control major variable in their investigations
Performing and Recording
Select and use tools for measuring
Make observations and collect information that is relevant to a given question or
Communication and Teamwork
Communicate question, ideas, and intentions, and listen to others while
Objective: For students to design and construct their own pulley systems based on the
story of Rapunsel. Students will be introduced to the concept of the compound pulley
system. Students will observe and demonstrate the differences between using simple and
Version of the story of Rapunsel
Pencils, paper cups, screw hooks, string, several pulleys, plywood
board, spring scale
Small weights (washers, bolts, etc...)
Comparing Pulleys Worksheet (see bottom of file)
Group Work Rubric (see bottom of file)
1. Read the story of Rapunsel to the class. Although this story is probably familiar to
many of the students, reading the story again will refresh the students' memories.
2. After reading the story, ask the students where a pulley system could have worked
within the story. Other than climbing up Rapunsel's hair, what other way could the
Prince have entered into the castle? What if Rapunsel was able to build a compound
pulley from materials that she just happened to have inside the turret?
3. Teacher will explain to students that a compound pulley system is a system that uses
more than one pulley to lift or move loads. Since Rapunsel would be trying to lift the
prince, a compound pulley system would offer more of an advantage to lifting this heavy
4. Divide students into small groups. Have students use their imaginations that the paper
cup was a bucket that Rapunsel had within her room, and that she also had rope and
hooks that were left in the castle turret. Students will be making both a simple pulley as
well as a compound pulley to compare which system would make this lift easier.
5. Using the plywood board, resting between two desks for support, screw in hooks that
students will use to place the fixed pulley (simple pulley) onto.
6. To make a simple pulley, with a pencil punch two holes in a paper cup on opposite
sides of the rim. Tie a string through the holes to make a handle. Thread the string
over a hook. Tie a loop at the end of the loose string so it can be hooked onto the spring
scale. Students have just made a simple pulley.
7. Students will now move on to construct a compound pulley system. Using another
paper cup, punch two holes on opposite sides of the rim. Using a piece of string, make a
handle for the cup.
8. Attach this handle to a hook. Pass the string through this hook, and run it over the hook
that is fixed to the plywood board.
9. Tie a loop at the end of the loose string so it can be hooked onto a spring scale.
10. Ask students how this pulley is different from a simple pulley system? How do they
compare their abilities in lifting a heavy load? What if the load they were going to lift
with their compound pulley was the Prince who was trying to get to Rapunsel? How
much force would they have to use?
*Teacher can demonstrate the differences in the pulley by using a single pulley system
with a weight to represent the Prince. The teacher can repeat this using a compound
pulley to demonstrate the difference in the force needed to lift the Prince. This will allow
students to observe the difference in the force needed to lift the load.
11. Still within their small groups, have students complete Comparing Pulleys
Worksheet (bottom of the page). Using various small weights, groups will compare the
abilities to lift loads using a simple pulley system, and compound pulley system using the
pulleys that they have just made. Students will be recording their results on the
worksheet. Students will be using the spring scale which shows the force (in grams) being
used to lift the load.
12. . Once groups have finished recording their results, each student will then graph their
findings. Student graphs will show the results of both the single pulley and the
compound pulleys that they used.
The teacher will be assessing student group work using the Group Work Rubric (see
bottom of the page)
Students will also be asked to respond in their journals to some of the questions the
teacher asked throughout the lesson: What is the difference between a single or
compound pulley system? How do they compare in their abilities to lift a heavy load?
Students are also encouraged to include in their journals any thoughts or ideas that they
had throughout this lesson.
Extension: Have students construct other pulley systems that have more than two
pulleys. Students will also be encouraged to change the weights that will be used for
their new pulley systems to lift. Students will be asked to record their results, and display
data in a graph.
For further investigation, have students complete the following as homework questions;
Level 1: Rapunzel wants to lift the prince, who weighs 75 kilos, using a compound
pulley with three pulleys. How much force will she need to use to pull on the rope to lift
Level 2: Draw a pulley system that will allow a child who can pull with a force of 10
kilos to lift a piano weighing 1000 kilos.
Group Work Rubric
work stayed on task
Staying on Task throughout the lesson completed. throughout
Little sharing members
No sharing of of ideas/work, worked will,
ideas/work not every shared
group member ideas/work
Group Member Communication
active within throughout
the group the entire
members acted members
through most appropriately
Behaviour of the lesson. throughout
Total = __________/9
Comparing Pulleys Worksheet
Test a simple pulley and a compound pulley to compare their abilities to lift
1. Using the pulley systems that you have made with the paper cups, place
weights in the cup.
2. Hook the spring scale to the other end of the string.
3. Lift the load by pulling on the spring scale.
4. Using the same weight in both the simple pulley, and the compound pulley,
record the results in grams as read on the spring scale. These results show the
force needed to lift the loads.
5. This should be repeated 4 or 5 times using various weights.
Simple Pulley Calculate the
Resulting Pulley Resulting Difference
Weight to be Force (g) Force (g) Between the two
Weight to be
Lifted (g) forces