*Grade level: 4th – 5th grades*

*Skills: Multiplication*

*Related environmental issues: Energy*

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 all of each light fixture?
- How much electricity can you save if you replace all of the 30 regular light bulbs with energy saving light bulbs?
- Say the average price of 1kwh-electricity in your area will be 9 cents for the next year. How much money does your family save for electricity in a year if you replace all of the 30 light bulbs with energy saving light bulbs now?

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Answer keys

- 200 x 30 = 6,000 (kwh)
- 60 x 30 = 1,800 (kwh)
- 6,000 – 1,800 = 4,200 (kwh)
- 4,200 x 9 = 37,800 (cents) = 378 dollars