How many plastic bags can you save?

Grade level:  4th – 5th grades

Skills: Multiplication & Division

Related environmental issues: Recycle

Area level: National, State, Regional, Household

Most of the plastic grocery bags are thrown away after used and many end up in the ocean. Those plastic bags have killed marine birds and turtles that confused plastic bags for jellyfish and plankton. It was reported that, on average, a single person use between 350 and 500 plastic bags in a year in the United States. Sarah used 420 plastic bags last year.

  1. The amount of energy used to make 12 plastic bags could drive a car for a mile.  With the energy to make 420 plastic bags, how many miles can a car drive?
  2. Sarah decided to start using reusable bags.  In 3 years, how many plastic bags can Sarah save?
  3. Some cities charge for using plastic bags to reduce the number of plastic bags used in the area. For example, in Washington D.C., customers need to pay 5 cents for each plastic bag. How much can you save in a year if Sarah moves to Washington D.C. and keeps using reusable bags for shopping?

Source: Earth Policy Institute, 2014. Plastic Bag Bans Spreading in the United States. & Thurston County (WA) Solid Waste, 2012. Reducing Our Use: Plastic Shopping Bags.


Answer keys

  1. 35 miles  (420/ 12 = 35)
  2. 1,260 plastic bags  (420 x 3 = 1,260)
  3. $21 (420 x 5 = 2,100 cents)