How much has the weight of plastic bottles changed?

Grade level: 3rd – 5th grades

Skills: Division 

Related environmental issues: Reduce /  Reuse / Recycle

The average weight of  plastic beverage bottles has changed over time. In 1980, five empty 2-liter PET bottles weighed 340 grams.  Now, nine 3-liter PET bottles weigh 378 grams.

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  1. Which weighs more, a plastic bottle in 1980 or now? And how much?
  2. Why do you think has the weight of plastic bottles changed? Explain.

Sources: PET Resin Association, Little-Known Facts about PET Plastic

 

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Answer keys

  1. 1980 bottle: 340 ÷ 5 = 68 (g)   Now: 378 ÷ 9 = 42 (g)    68 – 42 = 22 (g)     A plastic bottle now is 22 g lighter than that in 1980.
  2. Answers may vary: Hint 1) Lightweight plastic bottles reduce the use of plastic and raw materials  2) Lightweight plastic bottles reduce overall weight of the item and reduce energy consumed and CO2 emitted in the process of manufacturing and transporting the item. 3) Lightweight plastic bottles reduce plastic (and raw materials) use, so does the amount of plastic that has to be recycled.

 

Which car is clearer – Ford F150, Toyota RAV4 or Honda Civic?

Grade level:  5th grades

Skills:  Multiplication and division (decimals)

Related environmental issues: Air / Climate change / Energy

Area level: National, State, Regional, Household

Burning gasoline in motor vehicles is one of the biggest causes of air pollution in the United States. How much gasoline your car uses is strongly connected to how dirty the air in your area is. The table below shows how many miles three cars can run on one gallon of gasoline. Those three cars are the top-8 best-selling vehicles during the first half of 2018 in the United States.

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1. Which car can go half as far as Honda Civic on one gallon of gasoline?

2. An average American drives 280 miles a week. How much gasoline does an owner of each car use on average?

3. Which car among the three is more environmentally friendly? Why? Explain.

4. If the price of gasoline today is $3 a gallon, how much money does an owner of each car need to spend for gasoline in a week on average?

5. Which car among the three would you like to by? Why? Explain.

Source: 1) Business Insider, 2018 2) fuel economy.gov, 2018 3) U.S. Department of Transportation Federal Highway Administration, 2018

Note: Average Annual Miles per Driver: 13,476 miles (U.S. Department of Transportation, 2018)


Answer Key

  1. Ford F150
  2. Ford F150: 280 ÷ 16 = 17.5 (gallons)   Toyota Rav 4: 280 ÷ 25 = 11.2 (gallons)   Honda Civic:  280 ÷ 32 = 8.75 (gallons)
  3. Honda Civic: It uses less gasoline and emits less air pollutants into the air.
  4. Ford F150: 17.5 x 3 = $52.5  Toyota Rav 4: 11.2 x 3 = $33.6  Honda Civic:  8.75 x 3 = $26.25
  5. Answers may vary