Mr. Seemy and his class were talking about the plastic and paper bags that most people get from the grocery store each time they go. Chantel cited her reason for using paper bags instead of plastic. “Most plastic bags take at least a hundred years to break down and be absorbed by the earth.”

“Interesting point, Chantel,” responded Mr. Seemy, “but I just read about a new kind of plastic made from corn that is supposed to break down more quickly. It’s biodegradable.”

“Switching to corn plastic could be a strategy to help with the problem of too much trash in landfills,” said Chantel. “I think we should phase out regular plastic bags.”

“Not so fast, Chantel,” said Mr. Seemy. “You shouldn’t make a claim just because your teacher mentioned an article. Let’s do some research to find out more. Maybe someone in our class can help by doing an experiment and collecting some data.”

Chantel volunteered with her friend Angelo to create an experiment that buried bags in dirt.

Question: Do paper bags, regular plastic bags, and biodegradable plastic bags break down at different rates?

Hypothesis: Paper bags and biodegradable plastic bags will break down faster than regular plastic bags.

Materials:

• Samples of each bag material

• Scale

• Labels to stick in dirt

• Work gloves

• Shovel

• Small plot of land

Procedure:

1. Cut out a portion of a paper bag with a mass of 2,000 milligrams (2 grams). Do the same with regular plastic and with biodegradable plastic.

2. Bury them close to each other and label each spot.

3. Every two weeks, dig up each sample and measure the mass. Then rebury each sample.

Do Chantel and Angelo’s data tell you anything that relates to their hypothesis?

The students cut out 2,000 milligram samples of each bag material. Why is it important that the samples have the same mass? How is mass different from size? Do you think the samples were all the same size?

Discussion Question:

Even if paper bags biodegrade quickly, it doesn’t necessarily mean that they are the best choice for the environment. Why do you think these issues are so complex? Do you think scientists can help?