Online Lesson Plan
A machine is a device that does work. Machines do not increase the amount of work done, but they do make it easier to do the same amount of work. Machines make work easier by changing force or distance or by changing the direction of the force.
Lesson Plan by Kathy Jacobitz, science education consultant, Pawnee City, Nebraska.
Suggested grade level – 5th-8th.
- Students will investigate simple machines in their lives.
- Students will be able to identify each simple machine.
- Students will calculate the formulas used with simple machines.
- Students will be able to explain; force, effort, and work.
- Students will be able to draw or build a machine using two or more simple machines.
The three simple machines; the lever, the pulley, and the inclined plane along with their modifications; wheel and axle, the wedge, and the screw will be presented in this initial investigation.
Remember a complex machine is a machine made up of two or more simple machines.The introduction of the tractor, a complex machine, into agriculture in the 1930s made the work the farmers needed to do much easier. Many hired people were tractored out, their jobs were replaced with the tractor because now the owner of the farm could get more farming done by themselves.
- Students should review the entire Machines Section.
- Van Cleave’s Physics for Every Kid: 101 Easy Experiments in Motion, Heat, Light, Machines, and Sound by Janice Van Cleave.
- Mike Mulligan and His Steam Shovel by Virginia Lee Burton.
- The Way Things Work by David Macaulay (CD-Rom available).
- Green Eggs and Ham by Dr. Seuss.
- City Science – Grades 3-6 by Peggy K. Perdue and Diane A. Vaszely.
- Swinging Bears by Dave Youngs (AIMS).
- Teaching Physics With Toys sold by McGraw-Hill.
- Tortoise and Hare by Anita Ganeri.
- See How It Works: Earth Movers by Tony Potter.
- Betsy and the Vacuum Cleaner by Gvnilla Wolde.
- Force and Motion by Peter Lafferty.
- The Balancing Girl by Berniece Babe.
Click on any of the following for more information:
- KWL Charts.
- Journal Assessment Rubric.
- Rubric for Scientific Research.
- Assessment Checklist for the Scientific Research.
- Venn Diagram.
- Rubric for the Research Paper.
- Rubric for Group Work.
The simple machines investigations will be divided into the following parts
Part I: Lever
The lever is a simple machine made with a far free end to move about a fixed point called a fulcrum.
The three types of levers are, first, second and third class.
A first class lever is like a teeter-totter or see saw. One end will lift an object up just as far as the other end is pushed down.
A second-class lever is like a wheel barrow, the long arms of the wheel barrow are the lever.
A third class lever is like a fishing pole. When the pole is given a tug, one end stays still but the other end flips in the air catching the fish.
Ask your students to make a sketch of each type of lever mentioned above. Check the sketches in the journals to see if they are labeled correctly.
A fulcrum should be labeled.
First class level will have the fulcrum between the load to be lifted and the effort located where you would push down.
Second class levers find the load between the effort and the fulcrum. (Axle of the wheel barrow is the fulcrum.)
Third class levers find the effort placed between the load and the fulcrum.
Select a few sketches to show the class.
Reproduce an example of each lever type.
Now using these sketches review the location of load, effort, and fulcrum for each type of lever. Students should cut and paste these models into their journal.
Ask students to make a chart upon which they may record other examples of levers in their environment. Make a class chart and allow students to add to the list as they study the simple machine unit. (Example chart below.)
|First Class Lever||Second Class Lever||Third Class Lever|
|Teeter-totter||Wheel barrow||Fishing Pole|
Students will be asked to develop a general rule explaining their experimentation with levers. This investigation works well with a group of 3 or 4 students per group.
Washers – about the size of a quarter or half dollar
Empty film canisters or empty spool of thread
String and standard weights could be used to build a lever for testing their ideas. One takes the ruler, ties string in the middle to balance the ruler when they hold the string up. Make string loops and tie them closed. The loops fit over each end of the ruler so you may hook the weights on the string at each end. The other choice is to use the ruler as the board of the teeter-totter. Place a film canister under the ruler at the center of the ruler. The ruler should balance. Then place weights on the ruler at various locations later in the investigation. Washers work well for weights. Record the weight of a washer. Students may tape together washers to have larger weights and these will work in place of standard weight sets. If tape is used to hold washers together your students will need to weigh the total package to be used in the investigation.
Students need to make predictions on the following investigations in their journal before they do the testing. Each group works through the following situations and records the data in the journals. Following the investigations have a class data record collection location for students to record their data from their groups. Students should average the results and record the chart in their journal.
Allow the students time to revisit their general rule in the journal after each set of activities.
After the first activity they need to make a general rule that explains how levers work.
After all activities develop a class rule for levers.
Playgrounds in the 1930s had a see-saw as part of the play area. Make sure one is available at your school before trying this adventure in physics.
Students will need to take their journals along to the play area. You will need meter sticks, two or more students of about the same weight (Volunteers work best). Record student weights by using a bathroom scale or other scales at your school. Record student weights in grams, kilograms and pounds. (A great place to work on metric conversions.)
All students should calculate their own weight into metric units and place it in their journal.
Balance the see-saw with two students who weigh about the same; the see-saw should be centered on the support bar. Both riders are at the same distance, measure the distance in cm, meter, and inches.
Students need to predict what will happen if one rider leans forward?
Experiment by having one rider lean forward. Record what happened in journals.
Balance the two riders again.
Predict what will happen if one rider carefully leans back? Record the results. You as the teacher should stand behind the student leaning back for safety reasons.
The teacher or adult and a student volunteer, who weights less than the teacher, become the riders on the see-saw. Give the adults weight in kg and let the students do the math. Predict what will happen if both rides set on the see-saw at the far end of each side. Riders get on the seesaw and everyone record what happened in their journals.
Have students independently use all they have observed and learned to explain the results from the seesaw adventure. Ask the students to tell how they would balance the last two riders.
Sketch and explain their ideas in the journal.
Try some of the student ideas for balancing the adult and student. Make sure the distance is measured for each rider when they are finally balance on the seesaw. Record all data and observations in the journal.
Students should describe in the journal the relationship they have discovered about levers.
Sketch the seesaw and label the following: load, effort, distance and fulcrum.
Discuss student ideas about the relationship they have discovered about levers. Write it on the board or on a large paper. Remember it can be changed at a later date based on more data.
Washer Adventure Question:
What happens when the distance is changed between the fulcrum and the effort force?
Materials: Per Group
30 cm ruler
Depending on the design for the balance you will need:
- Place a pencil or film canister under the ruler at the 10 cm mark. Fulcrum.
- Push down on the 30 cm mark. Effort Force and the effort direction is down.
- Move the pencil to the 20 cm mark and again push down – effort force. Why is the effort force different in the above case?
- Label a sketch of the ruler set ups and label the effort, load and fulcrum on each sketch.
- What class lever is this?
- If the effort force is down which way is the load force?
- Explain how a crowbar is a first class lever.
- Explain how a pair of scissors is a double lever of the first class. How is this possible?
Perform a KWL on levers and debrief. Did the class generalization about levers change or stay the same?
Part II: The Pulley
Perform a KWL on pulleys. Journal responses followed by a class KWL.
A pulley is a simple machine made with a rope, belt or chain wrapped around a grooved wheel. A pulley works two ways. It can change the direction of a force or it can change the amount of force. A fixed pulley changes the direction of the applied force.
Example would be raising the flag up a pole. A moving pulley is attached to the object you are moving.
Your students will explore the pulley however major calculations will be addressed in other science classes.
Before each activity have students make predictions, do the activity, give students time to respond to the results in their journals then debrief before going to the next activity.
How much can you pull?
Materials per group: (You could decide to do this as a demonstration.)
2 firm rods, wooden or metal (broom handles work great)
a rope – 10-20 meters
2 pair of gloves
In this activity your students will use the rope to try and move one or two students. Have the students work carefully and always pull on the rope with an even, not jerky, force.
- One student should sit in a chair on a smooth floor, and hold a rod with both hands. The rod should be horizontal to the floor, tie the rope in the middle of the rode. Another student, wearing gloves, should grasp the rope about 4 meters from the chair and try to pull the person with the rope. Describe how hard it is to pull the chair and person. Journal response and discussion.Now have two students sit in chairs about 2 meters apart. Each student should hold a rod. (Horizontal) Take the rope from the tied rod and loop it over the other rod and back in the direction of the first student. Make predictions about the force needed to pull the student. A third student should pull on the rope. Record results and debrief. Ask students to design other ways they would like to test. What happens if more loops are made? What happens if they increase the number of ropes? Record results and make a conclusion about pulleys.
- Make a list of the ways pulleys are used in our everyday lives. a.) Raising the flag; b.) Lifting a motor from a car.
- How was the pulley and lever used on the farm during the 1930s?
Perform a post KWL for the journal and the class. Debrief.
Perform a KWL on inclined planes in the journal and compile a class KWL.
An inclined plane is a simple machine with no moving parts. It’s simply a straight slanted surface with one end higher than the other, like a ramp.
How can changing the height of a ramp affect the force?
Materials per group of students:
Medium Thick Rubber Bands
2 Thumb Tacks
Small board or cardboard – 34-45 cm long
Block or some weighted container
Note: It would add a control if all groups use the same length of inclined plane.
Predict results before each investigation. Journal Response.
- Stack three of the books together.
- Put the board against the books to create an inclined plane.
- Attach a rubber band to the ruler at the zero end.
- Observe and record the distance of the hanging rubber band.
- Tie the string to the unattached end of the rubber band and attach it to the block. (Set length of string as a control.)
- Lift the block up in the air and observe how far the rubber band stretches, record in the journal.
- Place the block at the bottom of the inclined plane. PREDICT What do you think will happen as you pull the block up the inclined plane? Do you think the rubber band will stretch more or less than when you lifted the block straight up?
- Pull the block up the inclined plane and observe how much the rubber band stretches. Record this measurement in the journal. Discuss the results only after students try to explain what they think happened in the investigation. Is an inclined plane a machine? Defend your response in your journal.
- Now repeat the investigation you just completed by using five books instead of three books. Predict and record the data in your journal. Discuss the results in the journal.
- Create a chart for all the group data and calculate an average result. Repeat the investigation again using another rubber band just in case the rubber bands have a different amount of stretch. What other ways can you think of to make the test more accurate?
- How did the stretch length of the rubber band change when you used the inclined plane?
- What other changes did you observe?
- How did the steepness of the incline plane affect the force needed to pull the block up the incline plane?
- Analysis: Distance is represented by the length of the incline plane and force is represented by the length of the rubber band stretch, calculate the work in each trial with the three books and five books. Force x Distance = Work.
- What inclined planes were used on the farm during the 1930s? Add these to the other list of simple machines.
Use all safety conditions around a slide.
- On a tall slick slide, slide half way down; then stop yourself by carefully grabbing the slide. Next, let yourself slide the rest of the way down. No extra push. How does your final speed compare to the speed you travel if you let yourself slide all the way from top to bottom without stopping in the middle? Slide all the way down if you don’t remember what the speed felt like from top to bottom without a stop. Record in journal and discuss the results back inside. One could calculate velocity of the student by taking the distance of the slide dividing it by the time it takes the student to travel down the slide. V = D/T.Design an experiment that will prove or disprove the first experiment with the slide. Use a smooth basketball, kickball or volleyball in the testing. Use the science investigative process for the test. Record all information needed, get your instructors approval, collect the data, and report results to the class from your journal.
- Design an experiment using two or three balls of about the same size and hardness but of different weights. Roll them down from the top of a slide, release at the same time, measure how far they travel after leaving the slide and before hitting the ground. Predict results first then test three times and average the data. Which traveled farther? Why? Which hit the ground first? Why?
Note: A forward moving object has momentum that keeps it moving forward until it his the ground or another object.
- Predict what will happen if, you take a softball with you on the slide. A wastebasket will be placed about two feet from the slide near the bottom. As you pass the wastebasket toss the ball sideways into the basket. What happened? Why? Does it usually fall in front or behind or in the basket? Why?
Note: Objects gain speed (accelerate) as they fall. Speed = Distance x Time. Calculate the speed of the student and the ball.
- Compare and contrast speed and velocity, based on the above investigations.
- Why are slides flat at the bottom?
- What simple machine would you use to get a person in a wheel chair up four steps into a building?
- What simple machines did the Egyptians, Aztecs or Mayans use to build their pyramids?
More simple machines maybe added to this list following the next investigations, so please have them leave space.
Perform a post KWL for the journal and the class.
Part IV: Wheel and Axle
Perform a KWL in the journal and then for the class on wheel and axle.
A wheel and axle is a modification of a pulley. A wheel is fixed to a shaft. The wheel and shaft must work together to be a simple machine. Sometimes the wheel has a crank or handle on it. List as many wheel and axles on the 1930s farm list then add as many as you can discover in the journal.
Examples: A doorknob and roller skates.
Use the following materials per group of students to design an investigation. List all controls and variables in the journal. Use the investigative science form.
Empty spool of thread
two paper cups; string
a hole punch.
List the procedure and get approval from your instructor before starting the testing. Record all the observations and data. Write a conclusion based on the data you collected.
Perform a post KWL in journal and for the class. Discuss which procedure designed by the students worked the best.
Part V: Wedge
A wedge is a modification of an inclined plane that moves. It is made of two inclined planes put together. Instead of the resistance being moved up an inclined plane, the inclined plane moves the resistance.
Perform a KWL for the wedge in the journal and a class KWL.
Build a wedge to answer the following question. What happens when the wedge is pushed between a stack of six books? Follow the scientific investigation format (Click Here for a form.) Discuss with the class how a wedge is a simple machine. Add wedge examples to the class list ideas for simple machines. Example = axe.
- How were wedges used on the farm during the 1930s?
- Write a story about using a wedge to help someone.
- Perform a post KWL in the journal and then compile a class KWL.
- Add to the list of wedges the new discoveries the student made.
Part VI: Screw
Perform a KWL in the journal followed by a class KWL.
A screw is a simple machine that is like an inclines plane. It is an inclined plane that wraps around a shaft.
Which screw is easiest to screw into a block of wood? Is it the one with a large number of threads or a small number of threads? Why?
Materials: (per group)
A Block of Wood
Scrap Lumber – at least 5 cm thick
Four Screws – the same length with various number of threads.
Make predictions as to which threads will be easiest to screw into the block of wood.
- Take the screw with least number of threads (grooves).Screw it into the block of wood until it is within a nickels height of the block of wood. (You could get a nickel between the block of wood and the screw head.)
- Take the next three screws and repeat step two. Record in the journal what you observe. Compare the effort needed to screw into the block of wood.
Compare and contrast the data to write the conclusion. Perform a KWL for the screw in journals then develop a class KWL. List all examples for the screw on the simple machine chart.
- If the screws with different number of threads were straightened out what would the inclined planes look like? Take a string or thread around the grooves or threads then straighten out the string. How different are the inclined planes? Which would be easier to climb if the same distances were placed on a dock? Why?
- Why do mountain roads go around the mountain?
- Could you pull out the screws with your fingers? Why do we use tools?
- Who develops tools? Why? What tools have been developed in Nebraska for farmers?
- Why do we use simple machines?
- What have you learned about simple machines that you didn’t know before?
- The new tornado slides go around and around. Why do you think they decided to build them with this design? Do you go faster or slower on a tornado slide or a straight slide? How would you test your hypothesis?
- How tall would a tornado slide be if you straightened it out?
- How do machines save energy?
- How did new tractors (complex machines) introduced during the 1930s impact farm families? (Positively and/ negatively.)
Bring in a bicycle that has gears and/or provide a drawing of a bicycle for the students to cut and paste in their journal. A bicycle is a complex machine made up of simple machines. Find as many simple machines as possible label them on a sketch in each journal their own journal then compile a class list followed by a discussion.
- Why have gears on a bicycle? Why start in a low gear? Why change gear to a higher gear? What happens when you change gears?
- Select a complex machine of your choice. Sketch or find a picture of the machine and paste it in the journal. Label all the simple machines you discover in the complex machine.
Extensions and Research Questions:
- What kind of simple or complex machine would you use to lift a pickup motor out of the pickup by yourself?
- A can opener, tire tools and crowbars are all examples of levers. Pick one, make a sketch, label and explain how it works.
- Compare removing the lid of a paint can with a coin, a short handled screw driver and a long handled screw driver. Explain your conclusion.
- Write a story about the practical applications of simple machines in your life.
- What were the simple machines in Mike Mulligan and His Steam Shovel by Virginia Lee Burton. Advances in shovel designs caused Mary Anne and Mike Mulligan some problems. What were the problems and how did Mike solve the problem. Write a story about the changes the tractor brought to the farming community during the 1930s. How were the problems solved in America?
- Measure the angles made when the inclined plane was made with three books and five books. Explain the results in terms of how it increased or decreased the ability to move an object up the incline.
- Use gear ratio to explain the gears on a three vs. ten-speed bike.
- Students may design a complex machine, using simple machines, to make a machine to perform a given task.
- Catapults are complex machines that are easy for students to construct. Students could try to build a catapult to launch a ping- pong ball.
- Toys are also complex or simple machines. Have a student select a toy and explain the simple machines found with a toy. Perform a post KWL for the simple machines and discuss the class results.
Perform a KWL for pendulums, kinetic energy and potential energy.
Potential energy is often called stored energy, whereas, kinetic energy is the energy of motion. If you stretch a rubber band between your fingers, it represents potential energy, let the rubber band go and it is kinetic energy. Energy is constantly changing from the potential energy to kinetic energy and back again. The process of this change in energy is called the transfer of energy.
The pendulum is one example of the way energy changes and is consumed. When a pendulum reaches the top of its swing, it has potential energy because of its position. As the pendulum swings through the lowest point of the swing, it has only kinetic energy. This energy becomes potential as the pendulum again reaches the top of its swing. This back and forth movement eventually slows down and stops due to friction and the resistance of air. But the energy is never lost, it is simply changes to heat energy.
The Law of Conservation of Energy states
(1) Energy cannot be created or destroyed
(2) it may develop from matter and turn into matter.
Children during the 1930s had swings quite similar to those we have today. Allow the students to swing thinking about when they are experiencing potential and kinetic energy. The swing is a pendulum that uses gravity to pull the students down from the high point of the pendulum. Students need to journal about this experience.
Will the length of the string attached to a washer (use all the same size of washers) impact the frequency of a pendulum?
Note: Frequency will be the number of times the washer tied to a string moves back and forth in one minute. A complete movement back and forth is counted as one. Repeat at least three times to calculate an average. Start all strings at the same height of the swing.
Chart Idea:Swing Number
Length of Swing
What relationship did your students discover between length of string and its frequency?
Make sure students graph the results by placing the pendulum length (Independent Variable) on the x axis and the frequency (Dependent Variable) on the y axis.
What would be the impact if you increased the mass (Added more washers) and repeated the above investigation?
Make a data collection chart or table and graph results. Record the time required to make three swings.
Students first need to write a conclusion based on the data collected for question #2, then compare and contrast the two investigations.
Perform a post KWL in the journal then compile a class KWL. Ask the students to create a list of as many pendulums as they can think of as a class.
- Which has a higher frequency, a grandfather clock or a cuckoo clock? Why?
- Ask students of different masses to swing on the same swing (pendulum) to test the results of question number two. Record all data and make sure students do not pump or shift their bodies in anyway since it would impact the results. The time for a back and forth swing motion is called the swing’s period. The students would need to be released at the top position of the pendulum.
- When you pump a swing, do you increase or decrease its period?
- What do you change by pumping as you swing?
Revisit the KWL to see if more information or questions need to be added or changes.
Part VIII: Green Eggs and Ham by Dr. Seuss
Explain and defend your answers in your journal about the physics found in the book, Green Eggs and Ham by Dr. Seuss.
- Sam I Am is holding ham and eggs on a tray on page 11. What form of energy do the green eggs and ham possess at this instant? Why?
- What would happen if the hand machine was reeled in instantly by Sam I Am?
- Using arrows, to show what would happen to the equation: Work = force x distance – if Sam I Am Did Not use the arm and handle to turn the axle of this simple machine? Why?
- What simple machine is this?
- On pages 14 – 15, if Sam I Am positioned his grip closer to the hands on each handle, would it require greater force or less force to move the hands to an equal height of three meters above the floor? Why?
- On pages 18 -19, what are the forces acting upon Sam I Am at this instant? Are the forces equal? Why?
- On pages 22 – 23, which lock will exert a greater force on the rope knowing Sam I Am weighs 30 kg and the fox weights 10 kg? Why?
- On pages 24 – 25, what medium are the sound waves propagating through? Would they be faster or slower through a solid? Why?
- On pages 26 – 27, is Sam I Am traveling at the same velocity as the mouse? Velocity = distance divided by time. Why?
- On pages 32 – 33, what forces are acting on Sam I Am’s car at this instant?
- On pages 36 – 37, do you need light to see color? Why?
- On pages 38 – 39, what would Sam I Am’s car and the passenger car do if they became disconnected from the train engine? (1) They would stop instantly, or (2) They would continue at their same velocity for an instant and eventually decelerate to a stop, or (3) They would roll backwards since they were no longer being pulled forwards. Why?
- On pages 44 – 45, at this instant in time what energy does the train possess? Why?
- On pages 46 -47, what has happened to the energy the train had at this instant? Why?
- On pages 50 – 51, why do the bubbles travel to the surface of the water?
- On pages 52 -54, do the green eggs have a high amount of cohesion or adhesion in reference to the tray? Why?
- On page 62, use the formula: pressure = force devided by area to answer the following question. Would it take greater force or less force to stick the fork in the wood tray if the circumference of the tongs of the fork were increased? Why? Use arrows to explain what is happening on page 62.
Make sure others know why you are using the playground at an unscheduled time to have your students explore playground physics.
- Use metric units whenever possible.
- Use a stop watch if possible for the investigations.
- Be safe on the playground.
Simple machines or complex machines save us energy and do more work then we could do without them. Remind the students physics is all around us and even in stories.
Click on any of the following for a quick reference.
- KWL Charts.
- Journal Assessment Rubric.
- Rubric for Scientific Research.
- Assessment Checklist for the Scientific Research.
- Venn Diagram.
- Rubric for the Research Paper.
- Rubric for Group Work.
Formulas could be used to expand the previous study if you want to expand the simple machine unit:
1. Velocity = Distance divided by Velocity
2. Power = Work divided by Time
3. Distance = Velocity x Time
4. Time = Distance divided by Velocity
5. Force = Mass x Acceleration
6. K.E. = 1/2 mass x velocity squared (K.E. stands for Kinetic Energy)
7. P.E. = Weight x Height (P.E. stands for Potential Energy)
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