Energy systems
EnerJeeps
1. Turn a Motor On
Overview
Many students know how to connect a battery and bulb with a wire so that the bulb lights. In Lesson 1 students review their knowledge of electricity, and apply it to make a motor go. They discover how to reverse a motor and how to use a battery and motor to test for insulators and conductors. Finally, there is a discussion of switches, leading to a Switch Hunt: a scavenger hunt for switches at home.
Procedure
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Review of electricity: Lead a brief class review of electric circuits.(See a video.) Use chart paper to review what is needed to light a bulb with a battery and wire.(If the Penguin Race Toy is available, this is how to use it as a model of an electric circuit.) Basic concepts are Complete circuit: The battery, wire and bulb must be connected so there is a way for electrons to flow from the battery through the bulb and back to the battery. Voltage: Voltage is a measure of the amount of energy the battery supplies. The battery gives the electrons an “energy kick” that is enough for them to travel on their own through the rest of the circuit. In a circuit, the electrons lose their energy as they make a bulb light up, create a sound in a buzzer or make a motor turn. Current: Current is a measure of how many electrons are flowing through the circuit.
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What is a motor: First students brainstorm where they have seen motors. They are likely to identify gas-powered motors, but explain that here we are talking about electrical motors. A brainstorming list of where electrical motors are found might include an electric fan, washing machine, electric pencil sharpener,a vacuum cleaner, or an electric train. Then ask: What does a motor do? Develop the idea that a motor uses electrical energy to make something rotate. It converts electrical energy to kinetic energy, which means “energy of motion.”
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Turn the motor on: Distribute the wire, battery and motor to each student. The challenge is to make the motor run. Ask: How will you be able to tell when the motor is running? Provide time for students to experiment and record their findings on the Worksheet. Important safety note: Like other batteries, these cannot give you a shock. However, other forms of electricity are extremely dangerous. Under no circumstances should any student attach anything to a wall outlet or to an electrical appliance that is plugged in. Next, present the challenge of making the motor turn the opposite way. Review the directions in which something can rotate: clockwise (CW) or counterclockwise (CCW). Here is a video on direction of rotation. Provide students with tape. Each student should attach a little piece of tape to his or her motor, and observe the direction of rotation: Which way does it go, when viewed from the shaft end: clockwise or counterclockwise? Which way does it go, when viewed from the opposite end: clockwise or counterclockwise? What would you have to do to make it go in the reverse direction from each view? Provide time for students to experiment and record their findings on the Worksheet.
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Make a battery holder: A battery holder makes it much easier to work with circuits. Show students how to make one.
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Insulators and conductors: Students may have discovered that when the coated part of the wire (rather than the metal center) is touched to the battery, the motor does not work. The metal wire is a conductor. It allows electricity to pass. The coated part of the wire is an insulator. It prevents the flow of electricity. Ask students to
- Connect the end of one motor wire to the battery.*
- Place various objects between the end of the second motor wire and the other end of the battery.*
- Which objects allow the motor to run? These are conductors.*
- Which objects don’t allow the motor to run? These are insulators.*
- Students make a list of insulators and a list of conductors in their Science Notebooks.
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Class meeting: Discuss the following topics and introduce the homework:
- Batteries, loads and energy transformation: Introduce the term load for anything that electricity can run. The input to a load is electrical energy. The output from a load is energy in some other form.
- What form of energy goes into a motor? What form of energy comes out?
- What form of energy goes into a light bulb? What form of energy comes out?
- Switches: Ask students:
- In the circuits you have made so far, what did you have to do to turn them ON or OFF?
- When you turn a TV, light or hair dryer ON or OFF, what do you do?
- This discussion should pave the way for the Switch Hunt homework (see below).
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Outcomes:
- An electric circuit requires a battery (or other source), a load and a path that connects each side of the load to a different side of the battery.
- A motor converts electrical energy to mechanical or kinetic energy (energy of motion).
- To reverse the direction of a motor, reverse the way the wires are attached to the battery, for example, attach the red wire to the “—“ side of the battery and black wire to “+” terminal instead of vice versa.
- Word-wall words: These are words used in the lesson that may be new to students. They are not vocabulary words to be memorized, but words posted on the wall for use by students in their writing and speaking. These are the words in Lesson 1: Electric circuit, battery, source, electrons, model, current, voltage, complete circuit, electric motor, electrical energy, kinetic energy, direction of motion, clockwise, counterclockwise, load, input, output, conductor, insulator.
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Homework: A Switch Hunt. Provide the Switch Hunt Worksheet for students to list switches they can find at home or elsewhere. For each one, they should list where it is located, what it controls, and what you have to do to operate it. For example, a light switch is located on the wall, it controls whether electrical energy will flow to a light fixture, and you operate it by pushing it up (on) or pulling it down (off). Other ways you might operate a switch could be by turning a knob, sliding something, or pushing a button down and holding it.
