Simple machines unit: Inclined plane, lever, & pulley activities

First written by Alicia Powers and Jessica Probasco

Overview

A unit with plans, to review or develop a beginning understanding of simple machines through science explorations used by humans to develop understanding and tools for humans to use for survival and improve their quality of life. Simple machines introduced: inclined plane, lever, and pulley.

Contents Overview

Background information:

This plan is designed for students who have very little prior knowledge of simple machines. However, they probably should have some conservation skills, such as believing variables that affect machine systems will do so consistently, or is conserved (always be).

Related study topics:

Big ideas, concepts, facts, and outcomes

Big ideas

  • Objects can be explored to make claims about simple machines and the variables the affect how they change force and the distance and direction of the applied force (effort).

Related concepts and facts

  • Better decisions (claims) are made when information is verified, with evidence and reasoning, before being considered accurate and used to reason and develop explanations and models to understand the world and make decisions.
  • People make better decision when they understand and consider the positive and negative influences that effect their decision making.

Outcome

Use accurate verifiable information to consider and decide what is a simple machine and describe how it operates to provide an advantage.

Science concepts: physical, earth, life

Simple machines can change the direction, transfer a force from one place to another, increase or decrease the amount of a force, and increase or decrease the distance or speed of a force (effort force and distance is proportionally to resistance force and distance).

Related concepts

  • Machines cannot put out more work than is put in and no machine is 100% efficient.
  • Simple machines are tools used to make work easier.
    • Simple machines facilitate the transfer of energy.
    • Machines cannot put out more work than is put in.
    • Simple machines can increase force, but not work.
  • Effort is the force needed to move a load or overcome a resistance.
  • An advantage is a benefit obtained by using a simple machine.
  • MA (mechanical advantage) is either: The ratio between resistance force and effort force, or a multiple factor of the resistance force and effort force.
  • Load is a mass lifted or a resistance overcome by a simple machine.
  • If more than one force acts on an object along a straight line, the forces will reinforce or cancel one another, depending on the direction and magnitude.
  • Unbalanced forces change the speed or direction of an object’s motion.
  • Equilibrium is a state where the net forces is zero.
  • An inclined plane is a simple machine used to reduce the amount of force needed to lift an object over a distance.
  • A lever is a simple machine used to gain an advantage, such as making work easier.
    • A lever is a rigid bar that pivots around a point that is used to move an object at a second point by a force applied at a third point.
    • A lever is used to change the direction of the force needed to lift an object.
    • A fulcrum is the point where a lever arm pivots.
    • The location of the fulcrum determines how much effort is gained.
  • A wheel and axel is a simple machine.
  • A pulley is a simple maching.
    • A pulley can change the direction of the force
    • A fixed pulley is a stationary wheel with a rope or belt wrapped around it.
    • A movable pulley has a series of lifting strands, the more lifting strands it has, the less effort that is needed.
  • A screw is a simple machine (an inclined plane wrapped around a center).

Outcome

  1. Describe a simple machine.
  2. Use a simple machine for a mechanical advantage.
  3. Expain the different arrangements of simple machine along with the advantages and disadvantages for it use.
  4. Explain how a simple machine can create a mechanical advantage in exchange for greater motion.
  5. Explains how the effort force and the distance it is applied with a simple machine is related to the product of the resistance force and distance it travels. 
  6. Explain effort force and distance is equal to the resistance force and distance; and simple machines are tools that manipulate force and distance to gain a mechanical advantage. MA (mechanical advantage) is either: The ratio between resistance force and effort force, or a multiple factor of the resistance force and effort force.

Science inquiry, process, & perspective concepts, facts, & outcomes

Big ideas: Science (claim evidence & reasoning) can be used to understand and explain cause and effect in the world.

Related concepts and facts

  • An experiment can be created to identify variables and their effects on interactions by using if/then thinking.
  • It is helpful to have a tentative answer, or hypothesis, as we try to answer our question.
  • When I experiment I collect observations that describe how different properties change (become variables) when objects and systems interact. This helps me make claims, explain what is happening, and to predict what might happen in the future.
  • As we become more experienced at asking questions and making predictions, we improve our ability to make careful hypotheses from which we design experiments
  • Variables describe properties that change and can be used to explain interactions.
  • Relative position describes changes in positions of objects when they are moved relative to a common position.
  • Systems are used to describe objects that interact together.
  • Interactions can be explained by describing how variables change within a system and how a system interacts with other objects or systems.
    • Objects change.
    • Change can be observed and recorded as before, during, after.
    • Change is observed through properties of the object.
    • Change can vary.
    • Constancy Somethings stay the same and some things change.
    • Constancy can sometimes be observed during a very slow rate of a change process or focusing on a particular property.
  • Inquiry concepts
  • Process concepts
  • Perspective concepts
  • Habits of mind, attitude, dispositions
    • Curiosity and persistence are needed to solve and understand problems.
    • I can create a simple machine if I just keep trying and use the material given.
    • If one plan doesn’t work, I can try another.
    • I am capable of using science to better understand the world.

Outcome

  1. Ask questions, identify variables to explore, and create and implement plans that explore them to find answers to different questions.

Pedagogical Overview

Activities Sequence to provide sufficient opportunities for students to achieve the targeted outcomes.

Make sure students have the prior knowledge identified in the background information.

  1. Activity 1 - Inclined Plane
  2. Activity 2 - Jumping Erasers
  3. Activity 3 - Lever system relationship
  4. Activity 4 - Pulley system
  5. Activity 5 - Tug of War Pulley
  6. Activity 6 - Messages on a Pulley

Focus question

Unit focus question:

What do we call objects that do work?

Sub focus questions:

  1. What is machine?
  2. What do they do?
  3. Why are some called simple machines?

Materials

  • Rulers, wooden sticks, weights, paper, cardboard, plywood, spools, string, rope, tape, scissors, broom sticks, pulleys and other simple machines if available

Lab notes

References and other resources

 

Scoring guides suggestions (rubric)

Rotational motion (scoring guide)

Top level

  • Explains simple machines MA (mechanical advantage) is either: The ratio between resistance force and effort force, or a multiple factor of the resistance force and effort force. And the product of the effort force and the distance applied is equal to the product of the resistance force and distance the load moves.
  • Explains effort force and distance is equal to the resistance force and distance; and simple machines are tools that manipulate force and distance to gain a mechanical advantage.
  • Concretely A simple machine can make work easier. For example: A 100 gram load can be lifted 1 cm (100 g * 1 cm = 100 g/cm) with 5 grams of effort exerted over a distance of 20 cm.
  • Effort force is less than the load, but it needs to move a greater distance.
  • Identifies simple machines and claims they help do work.

Lower level

Lesson Plans

Activity 1 - Inclined Plane

Materials for each learner

  • 1 piece of paper, ruler, pencil, books, plywood or cardboard, weight (wooden blocks), spring scale
  • Lab notes

Focus questions:

  1. What is a simple machine?

Learning outcomes:

  1. Make an inclined plane and raise objects with it.
  2. Explain how an incline plane is a simple machine.

Suggested procedures overview:

  1. Put learners in groups, focus their attention, and assess their initial understanding of the focus questions.
  2. Use a board as an inclined plane to demonstrate how to raise a load.

TEACHER NOTE:

  • weight = force = mass * acceleration of gravity (9.8 m/s/s)
  • Newton is force (in SI) that would accelerate the mass of one kilogram one meter per second per second. (1 kg = 1 newton) Close enought for young learners to use kg, Newton, weight, & force interchangeably. Also olay to tell them they will learn the difference between mass, weight, an force in more depth later.

Exploration -

  1. Put learners in pairs.
  2. Select one of the following:
    • Show learners the materials and ask. What type of machine could you construct using these materials to lift these blocks (or weight) 20 cm?
    • How can you move these wooden blocks (or weight) 20 cm using less force than that it takes to lift them straight up (using the sping scale to demonstrate how much force is needed to lift them straight up (20 cm).
  3. Let learners explore and invent an inclined plane.

Invention -

  1. Ask.
  2. What type of machine have you constructed? inclined plane
  3. How does it work? Accept all answers now. Makes work easier. They can change force. Can decrease or increase force, but doesn't decrease the amount of work. They cannot put out more work than is put in.
  4. Tell them it is a simple machine.
  5. Have them draw a diagram to show how the distance the load is dragged up the incline plane is further than lifting it 20 cm straight up.
  6. Discuss the advantages and disadvantages of the machine.
  7. Ask. How does the inclined plane make it easier? Spreads the force over a longer distance.
  8. Discuss where an incline plane might be used and why it is used in that situation. ramps
  9. Why are wheel chair ramps so long? easier to climb, need less force, need to spread the force over a greater distance to make it easier to navigate.

Discover

  1. Ask. How could you move a stack of books from the floor to the top of their desks.
  2. Discuss the possible machines that could be used to accomplish this task.
  3. Give the students the materials and have them create a machine from those materials that can be used to move the books.
  4. Give students time to work in small groups.
  5. Come back together and have each group explain their machine. Discuss the advantages and disadvantages of each set up. Did the set ups have steep or gentle slopes? Have each student try the different inclines and rank them in order from most difficult to move the books to least difficult.
  6. Have students discuss what they have learned about how inclined planes should be built and when they are most effective.

 

Activity 2 - Jumping erasers or washers or coins

Materials:

  • Ruler or about 40 cm stick with marks every cm, pencil, two weights (small and large eraser or washers or other weights with one being about five times the other), meter stick
  • Lab notes
Lever with erasers

Focus questions:

  1. How does a lever affect force or weight?

Learning outcomes:

  1. Create a lever.
  2. Drop the larger eraser at different points on the lever and measure how high the smaller eraser on the other end jumps.
  3. Explain how the lever system they used is a simple machine.

Suggested procedures overview:

  1. Put students in groups, focus their attention, and assess their initial understanding of the focus questions.
  2. Activity twirl zoomers.
  3. Describe

Exploration

  1. Put students in pairs.
  2. Demonstrate how to make a balanced lever by placing a ruler or stick on a pencil.
  3. Ask. What type of machine is it? simple machine, lever
  4. Ask. How could they explore where on the lever they should apply pressure to get the most advantage to lift a weight with a heavier weight?
  5. Discuss possible ways to explore and record data. Possible example: If they place one weight (small eraser or washer) on one end of the lever and drop a weight (heavy eraser or washer) at different distances from the fulcrum and record how high the small weight is launced when the heavy weight is dropped at different distances. (example above 5 cm, 10 cm, 15 cm, 20 cm, same weight dropped from same height about 20 cm, drop three time record all jumps, graph.
  6. Let learners explore and collect data as they have decided.
  7. Have learners record their results on a table so all can view.

Invention

  1. Discuss.
  2. Ask. Where was they weight dropped for optimal height?
  3. Where was the least?
  4. What statement can you make about a relationship for this system?

Discover

  • Could explore further with different weights and different lengths of levers (sticks).

 


Activity 3 - Lever system relationship

Materials:

Focus questions:

  1. What relationship can you make about a lever system?

Learning outcomes:

  • Explore and collect data to make a relationship about a lever system.

Suggested procedures overview:

  1. Put learners in groups, focus their attention, and assess their initial understanding of the focus questions.
  2. Select equipment and procedure to collect data for a lever system.
  3. Collect and analyze data to make a relationship for a lever system.

Exploration

  1. Put learners in pairs.
  2. Review previous activity.
  3. Ask. How they could explore a lever system to learn more about how the placement of the fulcrum affects the amount of force needed to lift an object?
  4. Generate different lever systems that can be used to change the weight being lifted (resistance) and the distance of a fulcrum to see how much weight would be needed (effort) to lift the weight (load).
  5. Set up the equipment and demonstrate how it will be used to collect the data.
  6. Can have different groups vary different variables.
    • process three or four times.
  7. Have learners record their results on a diagram or table so all can view.

Invention

  1. Discuss
  2. Ask. What relationhip can you make for the system?
  3. If you were trying to pull a nail and the claw hammer you were using was not pulling it out. It is really stuck, what would you recommend?

Discovery

  1. Discuss and demonstrate how the relationship can be described mathematically.


 

Activity 4 - Pulley system

Materials

Each student

  • materials to make a simple pulley: Wheel, pulley, spool, cord, string,
  • Lab notes -

Focus questions:

  1. How can you use a pulley to change direction?

Learning outcomes:

  1. Learners create a pulley to change direction.

Suggested procedures overview:

  1. Put students in groups, focus their attention, and assess their initial understanding of the focus questions.
  2. Activity

Exploration

  1. Ask. How can you use these materials to make a simple machine to change the direction of a force?
  2. Allow time for learners to discuss and create a plan to share.
  3. Share their plans.
  4. Let them revise their plans as desired.
  5. Let them impement their plan and collect results.
  6. to experiment before bringing the students together to discuss their machines.

Invention

  1. Have learners demonstrate their simple machines and share their results about how the direction of the force is changed with their machine.
  2. Ask. Was the force changed? no
  3. How could a pulley system be created to change direction and force?

Discover

  1. Create and explore pulley systems. next activity Tug of War Pulley

Activity 5 - Tug of War Pulley

Materials:

  • 2 broomsticks or comparable dowel rods, 5 meters of rope
  • Lab notes -

Focus questions:

  1. How

Learning outcomes:

  1. Explain

Suggested procedures overview:

  1. Put students in groups, focus their attention, and assess their initial understanding of the focus questions.
  2. Activity

Exploration

  1. Demonstration a tug of war pulley
  2. Select two learners to demonstrate.
  3. Give each a stick.
  4. Tie one end of the rope to one of the sticks.
  5. Have the students face each other, holding the sticks, with two hands, horizontally in front of them, about two feet apart. 
  6. Wrap the rope around each stick.
  7. Tell. the learners to pull backwards as you continue wrapping the rope around each stick.

Invention

  1. Discuss what happens.
  2. Record results on the board.
  3. Ask. What happens when the number of wraps around the sticks is increased?
  4. Ask. What are some practical uses for this simple machine?
  5. Discuss other ways in which to collect data to find a relationship of pulley system.

Discover

  1. Create an exploration to collect numerical data to determine a relationship for pulley systems.

 

Activity 6 - Messages on a Pulley Materials

Materials

  • two thread spools, 40 feet of string, 2 round pencils, paperclips, message
  • Lab notes -

Focus questions:

  1. How

Learning outcomes:

  1. Describe

Exploration

  1. Organize learners into groups and pairs.
  2. Show learners the available materials.
  3. Ask. How could you create a message system to communicate with another person by sending messages from one floor to another or from one house to another. Possible system:
    • Use the pencils as axels for the thread spool.
    • Tie the ends of the strings together to make a loop.
    • Select two people to represent each point of the system. Each person on a different floor or at a different window of a building.
    • Each person holds the ends of one pencil with the spool.
    • Wrap the string around the spools to create a pulley system.
    • Have two more learners represent the messangers.
    • Give each a message and paper clip to attach their message.
    • Attach and send messages.
  4. Explore sending and receiving messages.

Invention

  1. Discuss the efficiency of such a system and what other uses it may have.

 

Lab Notes for activities

Lab notes 1 - Inclined plane

Materials

  • weight, cardboard or plywood, books, spring scale

 

Challenge

Move a weight up from a lower to higher level by using less force than lifting it straight up.

 

Designs

 

 

 

 

Describe what you will do and did.

 

 

 

Hint: Does the diagram include two distances (distance the load is dragged up the incline plane and the height straight up from bottom to top. And two weights.

 

How does it work?

 

What are the advantages and disadvantages of an inclined plane.

 

Ask. How does the inclined plane make it easier?

 

 

 

Lab notes 2 - Jumping Erasers, Washers, or Coins

Lever with erasers

Materials

  • Ruler or 40 cm stick with marks every cm, pencil, small and large eraser, washer or coin, meter stick

Challenge

Launch objects from different positions on a lever, measure their height, and determine a relationship.

Designs

Describe what you do.

 

 

 

 

Data

Use a (● drop one, + drop two, * drop three)

ten x ten grid

 

Describe what you learned.

 

Lab notes 3 - Lever system relationship

Materials

Challenge

Collect data or evidence to determine a relationship to use as a model for a lever system.

Designs

Describe what you do.

 

 

 

 

 

 

Data

ten x ten grid

Relationship

Lab notes 4 - Pulley system

Materials

  • String, or cord, tape, weights, fastners
  • Ideas to use as a pulley: Spool, dowel, round pencils, pulley from Knex, or other toys.

 

Challenge

Create a simple machine to move a load in a different direction than the effort force.

 

Designs

Describe what you do.

 

 

 

 

 

 

Explain how it works.

 

Lab notes 5 - Tug of War Pulley

Materials

  • Broom stick or other round dowels, rope.

 

 

Challenge

Increase the force used to pull two objects (people) together.

 

Designs

Describe what you do.

 

 

 

 

 

 

Explain why it works.

Lab notes 6 - Messages on a Pulley

Materials

 

 

Challenge

 

 

Designs

 

 

 

 

 

 

Describe what you do.

 

Material Sheets

 

 

 

Dr. Robert Sweetland's notes
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