Using wind-up toys and cars to understand energy and energy transfer
Grade level(s):Elementary School (K-5)
Topic:Energy and motion
- Energy is the ability to do work. Energy can change and move things.
- There are different forms of energy for example stored (potential) energy and kinetic (movement) energy.
- Energy can be transformed from one form to another.
force, motion, energy, stored (potential) energy, movement (kinetic) energy, energy transfer, speed, time, distance, wheel, axle
What you need:
- wind-up toys (enought for every student or every pair of students)
- rubber-band propelled cars (one for every pair or group of 3 students)
- measuring stick (one for every pair or group of 3 students)
- stopwatches, timer (one for every pair or group of 3 students)
Part 1 of the lesson (Exploration of wind-up toy): Students make observations by themselves or in pairs and discuss their ideas with a partner.
Part 2 of the lesson (Rubber-band cars investigation): Students work in pairs or groups of 3.
Part 1: Classroom
Part 2: Space with room for car race tracks. Large classroom, school yard, cafeteria, etc. Smooth surfaces will work best for the car races.
- Part 1: ~45min
- Part 2: 60-90min
This is a two part lesson:
Part 1: Students will explore wind-up toys and try to explain the mechanism of the toy's motion, learning about the concepts of stored and movement energy and the transfer from one to the other.
Part 2: Students engage in an investigation to observe, measure, compare, and predict the motion of rubberband-propelled car.
It is helpful if students have experience measuring time and distance using tools (meter stick/measuring tape, stopwatch).
- Students are able to use observations to determine and describe cause and effect relationships in the movement of wind-up toys.
- Students can identify two different forms of energy (kinetic and potential) and explain how one form gets transfered to the other.
- Students can plan and conduct a simple investigation to explore different factors effecting speed and distance of a moving toy car.
Energy is "the ability to do work", it is how things change and move. Energy is everywhere around us and takes all sorts of forms. It takes energy to cook food, to drive to school, and to jump in the air.
There are many forms of energy, but they can all be put into two categories: Potential energy and kinetic energy.
Potential energy is stored energy and the energy of position. There are several forms of potential energy:
- Chemical energy is energy stored in the bonds of atoms and molecules. Batteries, biomass, petroleum, natural gas, and coal are examples of stored chemical energy. Chemical energy is converted to thermal energy (heat) when people burn wood in a fireplace or burn gasoline in a car's engine.
- Mechanical energy is energy stored in objects by tension. Compressed springs and stretched rubber bands are examples of stored mechanical energy.
- Nuclear energy is energy stored in the nucleus of an atom—the energy that holds the nucleus together. Large amounts of energy can be released when the nuclei are combined or split apart.
- Gravitational energy is energy stored in an object's height. The higher and heavier the object, the more gravitational energy is stored. When a person rides a bicycle down a steep hill and picks up speed, the gravitational energy is being converted to motion energy. Hydropower is another example of gravitational energy, where gravity forces water down through a hydroelectric turbine to produce electricity.
Kinetic energy is the motion of waves, electrons, atoms, molecules, substances, and objects.
- Radiant energy is electromagnetic energy that travels in transverse waves. Radiant energy includes visible light, x-rays, gamma rays, and radio waves. Light is one type of radiant energy. Sunshine is radiant energy, which provides the fuel and warmth that make life on earth possible.
- Thermal energy, or heat, is the vibration and movement of the atoms and molecules within substances. As an object is heated up, its atoms and molecules move and collide faster. Geothermal energy is the thermal energy in the earth.
- Motion energy is energy stored in the movement of objects. The faster they move, the more energy is stored. It takes energy to get an object moving, and energy is released when an object slows down. Wind is an example of motion energy. A dramatic example of motion is a car crash, when the car comes to a total stop and releases all its motion energy at once in an uncontrolled instant.
- Sound is the movement of energy through substances in longitudinal waves. Sound is produced when a force causes an object or substance to vibrate. The energy is transferred through the substance in a wave. Typically, the energy in sound is smaller than other forms of energy.
- Electrical energy is delivered by tiny charged particles called electrons, typically moving through a wire. Lightning is an example of electrical energy in nature.
How does a wind-up toy work?
A wind up toy consists of a spring (a thin, coiled metal strip) which is attached to a winder. The spring normally rests in an unwound position. When the winder is rotated the energy used to rotate the winder is stored in the spring in the form of potential energy. After releasing the winder the spring tries to unfold and the stored potential energy is converted into kinetic energy which is then transferred to the gears attached to the spring, which in turn rotates other gears or spins axles, making the toy roll forward, spin, flip or buzz.
Part 2 of lesson (Rubber-band cars investigation):
- Prepare the "race track": Mark off the start line of the track where students will line up their race cars. This can be done using chalk on the asphalt in the school yard or masking tape on the linoleum in the classroom or school cafeteria.
Lesson Implementation / Outline
Introduce the lesson by telling students that today you will explore what makes things move. Gently roll a ball away from you and have a student roll it back. Ask students what made the ball roll. Show students another, battery powered toy and ask them what makes this toy move. Hear students ideas and ask clarifying questions. Guide students towards the idea that there is energy stored in the battery that makes the toy move.
Tell students that they now will all get a toy and make very good observations in order to figure out how the toy moves.
Part 1: Observing wind-up toys
Show students the wind-up toy that they will work with. Explain how to wind it up and how to let it go inside the crate/box so that it does not fall off the table. Ask students to make and record careful observations. Walk around the classroom and guide students' thinking/explorations by asking some of the following questions:
- How many different parts of the toy can you see? Draw your toy and label the different parts.
- What happens to the different parts of the toy when you turn the winder knob?
- What happens to the different parts of the toy when you let go of the winder knob?
- How do the different parts of the toy work together?
- Try using different numbers of winds. What do you observe?
Give students 10-15 minutes to observe their toys and record their observations. (See attached student handout)
Collect all materials before moving on to the next part of the lesson.
Have students pair up and share their observations and their explanations about how the toy moves with each other.
Then gather the whole group and have some students share out.
Summarize students' observations and explanations and introduce relevant science terms.
Parts of the toy: Winder/winding key, spring, gear, feet
Movement: rotating/rotation, turn, potential/stored energy, kinetic/movement energy, energy transfer
Students record key vocabulary on their worksheet and then use the terms to describe how the wind-up toy works.
Part 2: What makes it go further?
Introduce the wind-up wooden cars to the students. Demonstrate how to attach and wind-up the rubber band. Let go of the cart and watch it drive. Have students talk and turn to each other to explain how the car moves, using the science terms from the last lesson. Hear some students report out their ideas.
Ask student how we might be able to make the car go further. Record ideas on board as students share out. Possible ideas might include:
winding up the rubber band more times, using different rubber bands, using more than one rubber band.
As a class, develop a hypothesis for each of their ideas:
"The greater the number of times the rubber band is wound up, the farther the car will go."
"The greater the number of rubber bands used, the farther the car will go."
Tell students that we all will look at one of the hypothesis together (# of turns). Discuss with students how we can test our hypothesis. How can we measure the distance the toy went each time? Show students the meter stick set-up and explain how to make good measurements (placing the front wheels at the 0 of the meter stick, measuring the distance by there the front wheels end up, letting go of the car without pusing it, etc.)
Show students the hand-out and explain that they will first establish a base line, winding up the rubber band 3 times. Tell them that they will do that 3 times/trials. Then students will increase the number of times they wind-up the rubber band and record those results, with 3 trials each time. Students calculate medians.
Students write # of turns and median distance on sticky dots and place it on the class graph on board. Discuss the results as class. Ask students to explain their observations/data. Can we predict how far the toy would go with 12 turns?
Extensions and Reflections
Read "Energy makes things happen" book by Kimberly Brubaker Bradley. As you read the book, record the different kidns of energy that are mentioned. Your table might look similar to the one below.
|Kinds of energy||What does it do?|
|Light||makes things bright|
|Heat||makes things warm|
|Movement energy (kinetic energy)||makes things move|
|Wind energy||makes things fly, sails sailboats across water|
|Stored energy (potential energy in oil, gasoline, food, wood)||burning gasoline moves cars, burning wood creates heat and light, eating food makes us move around|
|Solar energy||makes plants grow, makes things warm, gives us light|
Do the activity on page 33 with your students: Can you trace something that uses energy back to the sun? Maybe use the example given: Playing baseball. Or you could use the exampe of your students winding up the toy in the lesson above. Where did they get the energy from to wind-up the toy?