Students engage in an interactive "hot potato" demonstration to gain an appreciation for the flow of electrons through a circuit. Students role play the different parts of a simple circuit and send small items representing electrons (paper or candy pieces) through the circuit.
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- Colorado: Science
- International Technology and Engineering Educators Association: Technology
- C. Energy comes in different forms. (Grades 3 - 5)  ...show
- Next Generation Science Standards: Science
- Make observations to provide evidence that energy can be transferred from place to place by sound, light, heat, and electric currents. (Grade 4)  ...show
- Explain how a simple circuit works.
- Describe the functions of a switch and light bulb as resistors in a circuit.
- List several products that have been engineered to use electrical energy.
For the entire class to share:
- Colored construction paper
- Candy (optional)
For a class demonstration of how a circuit works:
- Two D-size batteries
- Small light bulb in a light bulb holder (available at hardware stores)
- Wire to connect the batteries to the light bulb holder
|Circuit:||The path through which electrical current flows.|
|Closed circuit:||An electric circuit providing an uninterrupted, endless path for the flow of current. It is like a closed circle or a completed circle. Current can only travel through a closed circuit.|
|Conductors:||Objects that allow the transfer of electrons.|
|Current:||The flow of electrical energy; the movement of electrons. A measure of the rate of flow of electrons — how fast they move.|
|Electrons:||Very small, negatively-charged particles.|
|Insulators:||Objects that inhibit the transfer of electrons.|
|Open circuit:||A electric circuit that is incomplete, or interrupted at some point. It is like an open circle because there is a break in the line of flow.|
|Power:||The product of voltage and current.|
|Resistance:||Objects or substances that prevent the passage of a steady electric current.|
|Voltage:||Amount of energy produced. Related to the force that pushes the electrons.|
Before the Activity
- Gather materials and make copies of the What Is a Circuit? Worksheet.
- Using markers, prepare several pieces of paper. Make four pieces with the following words: switch on (closed), switch off (open), battery and light bulb. Prepare enough remaining pieces of paper that say E or electron, for all the students. An alternative that is fun for the students, candy can be used as the electrons (E papers).
With the Students
- This demonstration involves the entire class. Students stand in a circle to show how a circuit works (see Figure 1). They form a "human circuit."
- At one end of the circle, identify one student as the battery by giving him/her the piece of paper with the word "battery" on it.
- At the middle of one side of the circle, identify another student as the "switch." Give this person two papers (switch on and switch off). Have this person begin by holding up the "switch on" paper.
- At the opposite end of the circle, identify another student as the "light bulb."
- The rest of the students in the circle are conductors (wire). They each have a piece of paper with a big E marked on it, representing an electron. (Or, alternatively, a piece of candy. No eating yet!)
- Students start passing the E pieces of paper (or candy) around the circle to the student next to him/her as if they were playing "hot potato." All the students, even the students being the "battery" and the "light bulb," help to move the electrons. Once the exercise is in process, point out how the current of electrons flows around and around the circuit as long as the switch is on (and there is a closed circuit).
- Next, have the student who is the switch occasionally switch their paper to the "switch off" or open circuit. This action makes a circuit break and the electron papers (or candy) must freeze, or stop moving around the circle.
- When the switch goes off, the flow of electrons stops, so the current stops. When this happens, the "light bulb" person stops glowing by lowering or "melting down" to the floor.
- When the student "switch" changes his/her paper to "switch on," the flow begins again and the electrons start moving like "hot potato" around the circle. Because it is turned "on," the student "light bulb" can jump up from the floor and "glow" again.
- Keep playing the game for a few minutes or until all the students understand how the current (or flow of electrons) moves through a closed circuit (closed circle or when the switch is on). Once they understand, students should know to stop the flow of electrons when the switch is turned off, or the circuit is open.
- Actively engage all students by re-assigning the roles of the switch, battery and light bulb several times during the activity. See if the students have ideas of other items that could use the flow of energy just like the light bulb.
- Assign the students the What Is a Circuit? Worksheet. Have them work individually or in pairs. After students finish the worksheet, have them compare answers with a peer or another pair, giving all students time to finish.
Activity Embedded Assessment
- The voltage? (Answer: Battery, because it stored the amount of electrical energy that was able to flow.)
- The current? (Answer: The electron papers [or candy] formed the current moving through the circuit.)
- The resistance? (Answer: There were several resistances, or resistors. The light bulb created resistance by changing the electrical energy into light energy. The switch was a resistance since it could open to stop the current from flowing. And, the students, representing the wire, were also resistors, keeping the current in place.)
- Open circuit? (Answer: The circuit was open when the switch was "off," the circle was broken, and the electrons stopped flowing.)
- Closed circuit? (Answer: The circuit was closed when the switch was "on, the circle was complete, and the electrons were flowing around the circuit.)
- For younger students, it may be easier to create a class diagram of the human circuit on the board, instead of completing the worksheet.
Dictionary.com. Lexico Publishing Group, LLC. Accessed September 28, 2005. (Source of some vocabulary definitions, with some adaptation) http://www.dictionary.com
Sharon D. Perez-Suarez, Jeff Lyng, Malinda Schaefer Zarske, Denise Carlson
© 2005 by Regents of the University of Colorado.
Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Last modified: February 26, 2015