Household Energy Consumption

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What You Need:

  • Paper for family electricity scorecard (4 columns: 1 with the light fixtures, 1 with how many watts each lightbulb requires per hour, 1 for the hours and minutes used, and 1 total column)
  • Pencil
  • Colored pencils or markers
  • Graph paper

What You Do:

  1. Start by explaining to your child that she will be conducting an investigation to help your family figure out how much energy you're using on lights that you commonly leave on in the house. Help your third grader select five fixtures that the family uses a lot, and the wattage of each one, using regular incandescent bulbs.
  2. Help your child identify how many watts each lightbulb requires per hour, and record it on the Family Electricity Scorecard.
  3. Now pick a typical 24 hour period, and invite your third grader to observe and estimate: How many hours and minutes does that light stay on? Write those results on the scorecard, too.
  4. Now it's time for some real-life math practice. On a piece of scratch paper, invite your young energy auditor to multiply the wattage of each bulb by the number of hours it's on. If your child is still struggling with multiplication, you can help by rounding minutes to the nearest hour; if your child is ready, however, you may also want to convert any extra minutes into a fraction of an hour, and multiply the exact number by the bulb's wattage. 
  5. Add the totals from each column, to make a grand total of wattage used.
  6. What's exciting now, of course, is to figure out what's the best way to save. Would it be possible to turn off the lights more? What difference would that time make? And, if you have purchased low-wattage flourescent bulbs instead, how much difference would they make if you used them instead of the incandescent bulbs?
  7. Finally, help your child make a graph for your family, using the data from the template. Put it on a bulletin board or on the fridge for the family to examine, and don't be surprised if next time, it's your third grader who takes the lead in reminding everyone that it's time to turn out those energy-guzzling lights!

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