Applied Science - Technology (3B)
Pre Lab 

  • Exploring how electricity makes a city move.
  • Investigating how you pay your energy bill.


  • electricity
  • kilowatt hour
  • meter cards
  • worksheet

Students learn how to read an electric meter.


Students do not really understand how important electricity is to our everyday existence. Public supplies of electricity were not available to countries until the late 1800's. England and the United States were leaders in the development of a public system of power generation. Urban areas were usually serviced before the rural areas. In the period between 1920-1950, the demand for electricity made the "power company" an important part of our everyday lives. Point out that there are different "types" of electric current in different countries. You can't plug a hair dryer bought in the United States into a European plug.

In the generation of electric power from water, fuel, or nuclear, the heat energy is converted into mechanical energy by a prime mover and then into electrical energy by a generator. A generator is based on the "dynamo" principle - a fast-moving substance which can generate electricity. This is much more complicated but it is not necessary to go further than this in the third grade.

  1. Many students may ask how electricity is moved. Point out any transmission or power lines. In California for example, much of the electricity is generated by hydroelectric power. If a power plant is close to your school, try to arrange a tour. Invite the janitor, or any member of the maintenance crew from the school district, to give a lecture to explain the power source at your school.
  2. People must pay for the luxury of electricity. Private electric utilities are regulated by state or city governments. The various laws require that power companies be permitted to earn a reasonable profit. But how do we pay for energy?
  3. A school's electric bills are based on two factors: the amount of electricity used, measured in kilowatt hours, and how much is used at any one time (or kilowatt demand). Schools have two meters; one meter to record the total kilowatt hours used; the other to record the largest number of kilowatts used at any one time.
  4. If students want to lower the school's energy expenses, they will need to do more than use less electricity. They will also need to keep from using a large amount of electricity at any one time. Example: If the cafeteria is preparing lunch from 9 a.m. to 12 p.m., students should ask the shop teacher not to operate the machines LAB this time. This will keep the school's electrical demand lower.
  5. Some of the portions of the lab sheet were designed by Pacific Gas and Electric Company. They will help your students see how electricity is recorded. Many places are a little more modern, but many old buildings still use a meter.
  6. To make a meter card you will need: brads, stiff paper (about 60 lb paper), pen, circle template
    A meter card helps gas companies read meters that may not be assessable to meter readers. Make 5 circles and number the circles as below. Put the brads in the center. Make a "hand" that students can rotate to any of the numbers on the rim. Students will use the hand to help read the meter.


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