*Grade level: 4th – 5th grades*

*Skills: Multiplication*

*Related environmental issues: Energy conservation*

The table below shows how much electricity each light bulb uses to light your room in 1 year.

- Your house has 30 light fixtures. How much electricity do you use during a year if you use a regular light bulb for each light fixture?
- How much electricity do you use during a year if you use an energy saving light bulb for each house’s light fixture?
- How much electricity can you save if you replace all of the 30 regular light bulbs with energy saving light bulbs?
- The average price of 1kwh-electricity in California was 21 cents in August 2018. How much money could your family save for electricity in a year if you replaced all of the 30 light bulbs with energy saving light bulbs in a year?

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Answer keys

- 200 x 30 = 6,000 (kWh)
- 30 x 30 = 900 (kWh)
- 6,000 – 900 = 5,100 (kWh)
- 5,100 x 21 = 107,100 (cents) = $ 1,071