Recycling Math

Michelle Jones Morgan Park High School
1744 W. Pryor Ave.
Chicago Il 60643
(312) 535-2550

Bob Foote Disney School


The teachers and students will have experience applying mathematics to
environmental problems. This will include classification, weight and
percentages of types of garbage, using a map with a scale to estimate distances,
using containers to measure areas, and identification of plastics using SPI

Materials Needed:

Activity I
Garbage, balances

Activity II
String, maps, rulers

Activity III
Individual and economy sized containers, rulers

Activity IV
Plastic containers in each of the seven SPI codes (on the bottom of container
inside of the three arrows).


Activity I
Given a bag of garbage, students will sort the materials into the categories of
paper and cardboard, glass, metal, plastic, and other. Food and yard wastes
should be removed prior to the lesson. After separation of the garbage, the
student should determine the weight of each category of garbage. After weight
determination, students should calculate the percentage of the total weight for
each category of garbage. To find the percentages first divide the weight of
each type of garbage by the total weight of all of the garbage, and then
multiply this number by 100 to convert the decimal to a percentage.

Activity II
Distribute maps of the East coast and direct the students to follow the route of
the Mobro 4000 (garbage barge). The route began in Islip, NY and went to
Morehead City, NC then to Florida, Alabama, Mississippi, Louisiana, Texas,
Mexico, Belize, the Bahamas and then back to New York. First have students
estimate the distance the barge travelled and then, using the scale on the map
have students measure the distance (on the water only) the barge travelled.
Have students discuss the environmental impact of such a trip and what it tells
us about the problems of solid waste.

Activity III
Using individual and economy sized containers, (cereal boxes, milk cartons, soap
boxes, vegetable cans) that have been opened and cleaned,
1. Have students measure the area of each container [rectangle= length X
2. Have students record the volume of each container that is printed on
the label.
3. Calculate the difference in the amount of packaging used to hold the same
amount of product.
4. Calculate the number of small cartons needed to have the same amount of
product as the large carton.
5. Which package is more environmentally friendly and why?

Activity IV
Have students sort a large variety of plastics by the SPI codes found on the
bottom inside of the triangle. Once the products are in the seven
categories, have the students determine which categories have the most products
and discuss if this has anything to do with the Chicago Blue Bag Programs
limitations of plastics 1 and 2 only. Have students try to find exclusive
physical or behavioral properties of each category of plastic. Tests can be
done to test transparency, creases when folded, squeaks when rubbed, smooth or
textured sides, etc.

Performance Assessment:

Students will be graded based upon ability to perform the correct calculations
according to the standard rubric.


Students should have learned about the impact of the volumes of garbage that we
introduce into the solid waste stream. Students will also have an opportunity
to practice mathematical calculations.

References: Using Mathematics From Your Backyard To the Great Wall. Everyday
Learning Corporation. Evanston, IL.
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