How much energy and money do new light bulbs save?

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.

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  1. 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?
  2. How much electricity do you use during a year if you use an energy saving light bulb for all of each light fixture?
  3. How much electricity can you save if you replace all of the 30 regular light bulbs with energy saving light bulbs?
  4. 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

  1. 200 x 30 = 6,000 (kwh)
  2. 60 x 30 = 1,800 (kwh)
  3. 6,000 – 1,800 = 4,200 (kwh)
  4. 4,200 x 9 = 37,800 (cents) = 378 dollars

How much water does it take to produce 3 eggs?

Grade level:  4th – 5th grades

Skills: Multiplication

Related environmental issues: Water

The table below shows some types of food you eat and the amount of water required to produce the food.

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  1. In the morning, you had 3 eggs. How much water did it take to produce 3 eggs?
  2. At noon, you had lunch with 4 friends. Each bought a bottled soft drink. How much water did it take to produce the water?
  3. Both you and your brother had 2 small bags of potato chips after school. How much water did it take to produce the potato chips?
  4. You and your brother had pizza for dinner. You had three slices and your brother had four slices. How much water did it take to produce the pizza?

Sources: Water Footprint and World watch Institute

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Answer keys

  1. 52 x 3 = 156 (gallons)
  2. 78 x 5 = 390 (gallons)
  3. 62 x 4 =248 (gallons)
  4. 92 x 7= 644 (gallons)