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.

 

How much food is wasted?

rade level: 4th – 5th grades

Skills: Multiplication

Related environmental issues:  Reduce, Reuse, Recycle

Have you ever thrown away food after you felt full and stopped eating? In the United States, 30% of edible food is spoiled and thrown away.  That is as big as each person throwing away $494 every year.

  1. You have 4 people in your family. How much can your family save in a year if food is not wasted at all?
  2. What can you do to prevent food waste?

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Sources: U.S. EPA (2016). Sustainable Materials Management Program Strategic Plan. page 6.

Note) The food waste (and loss) is equivalent to $161 billion annually.

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Answer keys

  1. $1,9764  (94 x 4 = 1,976)
  2. Answer may vary:Don’t over-serve food, Save and eat leftovers,Vacuum-pack unprepared or pre-cooked ingredients, Store food properly, Keep a record of your waste, Plan your meal before shopping