Lesson Overview

Students will learn how to read their home electrical meter, record the amount of energy their household uses each day for a week, and write a science report.

Target Grades: 3-5

Set Up Time: 15 minutes

Class Time: 1.5 hours over 2 sessions

Lesson Resources

Objectives

  1. Accurately read an electric meter.
  2. Make observations, collect data on home energy usage, and interpret results.

Guiding question: How do we know how much energy our house uses each month?

Educational Standards

ALASKA MATHEMATICS STANDARDS: 3.MD.4, 4.NBT.4

ALASKA SKILLS FOR A HEALTHY LIFE: D1, D2

ENERGY LITERACY CONCEPTS: 6.8

NGSS: 4-PS3-2

Lesson prepration:
  • Optional: Do the “Our Electric Footprint” lesson
  • Read the Background section below.
  • Preview the two versions of the student worksheet and decide which one you want to use.
  • Take a photo of the school electric meter(s) to show a local example of what the electric utility uses.
  • If you don’t know already, find out what the local residential rate for electricity is and whether most meters are digital or analog.
Gather Materials:
  • One Reading your Electric Meter worksheet per student (download from dropdown above)
  • One pencil/writing utensil per student
  • Optional: one clipboard per student

Knowing how to read and interpret the electric meter at your home can greatly increase awareness of your household’s energy use and how this energy use is higher on certain days (e.g., laundry day, weekends when household members are home all day, very cold days, etc.) and lower on other days (e.g., weekdays when kids are at school/parents at work, warmer days, etc.). An electric meter records energy usage so that the utility company can determine a household’s electric bill.

Energy = Power x Time: Electric meters measure energy in kilowatt-hours (kWh). This is the amount of power (number of kilowatts) used over a certain length of time (one hour): 1 kW X 1 hour (h)=1 kWh

Energy use of household appliances are usually rated in watts (W): 1,000 W = 1 kW

Example: How many kWh is uded by a 60 W appliance for 1 hour? First convert watts to kilowatts, then multiply by time: (60W X  1kW/1000W)  X 1 h= 0.06 kWh

In Alaska, the price for a kilowatt-hour varies greatly depending on location and fuel used for power generation, such as natural gas, hydropower, coal, or diesel. The average cost of electricity in the nation is about $0.12 / kWh, though energy costs tend to be higher in Alaska than elsewhere in the nation, especially in rural Alaska. In communities with high electricity costs, the state reimburses utilities for some of their costs to reduce electricity rates to residents – this is called the PCE (Power Cost Equalization) program. Households using less than 500 kWh per month get this rate, but if they go over 500 kWh, or for businesses, they pay the higher cost without PCE. In 2018, the price of electricity with PCE was $0.34/kWh in Unalaska, $0.24/kWh in Elim, and $0.22/kWh in Cold Bay. Without PCE, the price of electricity was $0.50/kWh in Unalaska, $0.52/kWh in Elim and $0.67/kWh in Cold Bay. Check a recent electricity bill or call your utility to find the current cost per kWh in your community. 

Electric Meter – A device that measures the amount of electricity used. Electric meters are used by electric companies to measure electricity use by their customers for homes or businesses, and portable electric meters such as the Kill-A-Watt meter can measure the electricity used by individual appliances.

Energy – The ability of a system to do work; this might refer to either potential or kinetic energy. Potential energy (stored energy) includes chemical, mechanical, nuclear, and gravitational energy. Kinetic energy (motion energy) includes radiant, thermal, motion, sound, and electrical energy. 

Kilowatt (kW) – A unit used to measure power. One kilowatt equals 1,000 watts (W).

Kilowatt-Hour (kWh) – A unit used to measure energy. A kilowatt-hour is the amount of energy used if you use 1,000 watts for one hour and is equivalent to 3.6 million joules and 3,412 BTUs.

Power– The rate at which work is performed or energy is converted; units of power include both an amount of energy and a length of time.

Scientific Method (Scientific Process) – The methodological steps involved to pursue knowledge which includes asking a question, conducting background research, creating a hypothesis, collecting data through observations and/or an experiment, analyzing the data, drawing a conclusion, and communicating the results.

Watt (W) – A unit used to measure power. One watt equals one joule per second (j/s). A typical incandescent light bulb uses 60 W to keep the light bulb lit for one hour.

Gear Up:
  • If time allows, complete the AK EnergySmart lesson “Our Electric Footprint” to introduce concepts of electricity usage and measuring.
  • If possible, invite a local utility representative into the classroom to present on how to read a meter.
  • Lead a class discussion about home energy use: Ask students what energy they use during the day and if there are certain days their family might use more energy and record students’ responses on a board. 
  • Another Gear Up is to take pictures of different meters and at different times, or to simply draw different meters on the board to have the students practice reading meters. This is good to do even with digital meters to get them used to finding and recording the numbers.
Activity
  • Instruct students how to read an electric meter that they are likely to see at their house, either analog (example below) or digital.
  • If not covered in the discussion, tell students that most homes have an electric meter outside so the utility company can track that home’s energy usage. While meters at newer homes are likely to give a numeric or digital reading output, older meters display with dials. This meter contains 4 dials which, from left to right, represent the thousands, hundreds, tens, and ones:
The dials on the electric meter above read “3,256 kWh.” Notice that some of the dials turn clockwise while some turn counter-clockwise. If the dial is in between two numbers, always read the smaller number. To determine the amount of energy used over a certain amount of time, subtract the original reading from the most recent reading (and the units are in kWh).
  • Explain to students they will use the scientific method to track their home’s energy usage for a week and write a scientific report on their findings.
  • Hand out the Reading Your Electric Meter worksheets and guide them through completing the question, hypothesis and materials sections in class.
  • Instruct the students to read their electric meter once per day at the same time every day for a week and record it on their worksheet. Invite them to take photos to verify readings. If they can’t use one at home, help them find an alternative like the school or local business.
  • Discuss the conclusion questions as a class, emphasizing how their and their families’ behaviors impact the reading on the electric meter.
  • Wrap Up
    • Ask them how they can reduce their electricity use. Examples include using LEDs instead of incandescent light bulbs, turning off lights, unplugging unused appliances, not leaving the refrigerator door open, running full loads in the clothes and dish washers, and more
    • Discuss why it is important to conserve electricity to save money, lower impact on the environment, and improve air quality.
    • Discuss how different communities pay different amounts for their electricity. If you are in a community that receives PCE, discuss the importance of staying below 500 kWh per month.
Extension
  • Have groups of three or four students graph their results on the same graph to illustrate how multiple data sets can be compared on the same graph, and how data compared between households.
  • Schedule a tour of the local power plant. Most utilities are open to having groups see their facilities.
Evaluation
  • Students were able to record data from their home electric meter.
  • Students participate in discussion about impacts on home electricity use.