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Circuits and Switches

Unit Summary

Learning about simple electrical circuits gives students some basic knowledge about electricity. This knowledge will enable them to more easily understand the complex circuits inside a computer. Computer circuits follow the same principles even if the components are not visible to the naked eye. The online lessons with readings, video demonstrations, and activities introduce students to:

  • The basics of electricity
  • Simple electrical circuits
  • Electrical flow
  • Conductive and nonconductive materials
  • Huge electrical circuits at a hydro-electric power plant
  • Mechanical and nonmechanical switches (transistors)
  • AC and DC current

Students will work online with electrical circuits like the one shown in the figure below.

Goals and Objectives
Students will:

  • Understand that an electrical current in a wire is a flow of electrons
  • Be able to construct a simple, working circuit
  • Understand conductivity of solids and how conductivity can be tested
  • Learn some of the terminology used in circuitry
  • Become familiar with the process of assembling and testing a variety of simple electrical circuits
  • Understand that an electrical current in a wire can be controlled (turned on and off) by a switch; the switch may be mechanical (with moving parts) or electronic (no moving parts)
  • Observe the action of a transistor in a simple circuit
  • Understand the construction of a transistor

Time to Complete Online Lessons: about 30 minutes


  1. Read the background information.
  2. Review and prepare for supplemental lesson ideas and group activities.
  3. Organize materials and equipment:
  • Student computers with an active Internet connection
  • Copies of the student handouts that you plan to use
  • Printouts of the interactive whiteboard images (optional)
  • A working flashlight (optional)
  • Tokens (optional)
  • Masking tape, aluminum foil, batteries, LED, or flashlight lightbulb (optional—used in Handout: Fun With Circuits)
  1. Have students complete the online activities.
    Throughout the unit, facilitate the development of new vocabulary introduced in this unit.
    Encourage students to use the new terminology of circuits correctly in their discussions and written work.
  2. Students who are not at the computer can work on supplemental lesson ideas and group activities
Student Handouts
The following handouts can be used with this unit to enhance learning. Each handout is briefly described below. To see the actual handout, click the link "handout."
Using Electricity

This handout helps students:

  • Understand our dependence on electricity
  • Differentiate between alternating current (AC) and direct current (DC)
  • Compare how electric current and water are delivered to our homes
Nonmechanical Switches

This handout  explains in text and diagrams how transistors work.

Fun With Cricuits

This handout  gives instructions on how to build a lightbulb circuit with:

  • Aluminum foil
  • Masking tape
  • Flashlight-type lightbulb or LED
  • 9-volt battery or C-cell batteries
Interactive White Images

The images linked below are pertinent to this unit. You can project the images on an interactive whiteboard and use them in class discussions or activities.

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