Recycling Plastics 101

Recycling Plastics 101 | Homeschool Science CornerRecycling is the act of reusing or re-purposing materials once considered to be waste.

We can recycle all kinds of items, such as batteries, glass, metal, paper, and plastics.

In today’s homeschool science corner, I want to share with you the basics about recycling plastics.

Why recycle plastics?

One of the most common materials to recycle is plastic. Many items, such as soda bottles, medicine bottles, baggies, PVC pipe, and Styrofoam containers, are made from this material.

It is prized for its durability and strength, but these strengths also mean that most plastics are not biodegradable. In other words, when plastics are buried in a landfill, they won’t break down in same way that paper and other organic material would.

So, it makes sense for us to try to re-purpose and reuse our plastic materials.

What happens when you recycle plastics?

Plastics are made from a variety of raw resin materials. These different types of resins don’t mix well together, so the first step in recycling is to sort the various types of plastic products into categories.

Once the items or sorted some plastics, such as bottles, are shredded. These shredded bits then undergo a process of extrusion to form plastic pellets that can be reused as raw materials in the formation of new plastic products.

Other plastics can undergo chemical processes that turn them into a light crude oil or into a carbon source that is used in the recycling of steel.

What types of plastics can you recycle?

The government has developed a coding system, called the SPI Resin ID Code, to identify the different types of plastics. The following chart shows how this coding system works:*

SPI Resin ID Code

Type of Resin




PET (Polyethylene Terephthalate)

soda & water bottles, medicine containers

Widely Accepted


HDPE (High-density Polyethylene)

Heavy plastic contains, like those for oil and detergent

Widely Accepted



Plastic pipes, shower curtains, medical tubing

Accepted at Some Centers


LDPE (Low-density Polyethylene)

Wrapping films, grocery bags, plastic baggies

Accepted at Some Centers


PP (Polypropylene)

Microwaveable plastic containers, like Tupperware

Accepted at Some Centers


PS (Polystyrene)

Disposable utensils, coffee cups, meat trays, packing peanuts

Widely Accepted


Other (Mixed Plastics)

Compostable plastics often labeled as PLA containers

Rarely Accepted

*See this article on for more information on the SPI Resin coding system

So products like plastic bottles and the Styrofoam used in packaging can generally be easily recycled. For other items, like plastic bags and shower curtains, you will need to check with your local recycling center first.

Recycling Vocabulary

Here are a few vocabulary words to go over as you study recycling plastics.

  1. Recycling — The act of reusing or re-purposing materials once considered to be waste.
  2. Biodegradable — Capable of being broken down by natural means, such as through bacteria or by the sun.
  3. Raw materials — The basic materials used to make a product.
  4. Product — A substance that is made for use and/or sale.

Books to Learn about Recycling

The following books would be good to read for a mini-recycling unit.

  • Recycle!: A Handbook for Kids by Gail Gibbons
  • Michael Recycle by Ellie Bethel and Alexandra Colombo
  • The Adventures of a Plastic Bottle: A Story About Recycling by Allison Inches

Activities for Recycling

Visit our Recycled Projects Pinterest board for activities and crafts that involve recycling.
Follow Elemental Science’s board Recycled Projects on Pinterest.
by Paige Hudson


  1. Paige, this is just in time as we prepare to attack DK Chemistry pages 54-55. I’ve collected lots of stuff from the recycling company and the village recycling rules here. I really want the Gs to be recycling experts and stop asking me if “this can be recycled or not.” Discernment and wisdom based on these lessons may be the biggest win from our attempt at eclectic-logic-stage-chemistry. Thank you.

    • No problem! There are some good informational articles on the linked Pinterest board that the Gs can read. Glad to hear that the ecclectic approach is working for you all this year!

  2. How timely! We just did an inquiry lesson on plastics last week ( My plan was to talk about recycling today!! 🙂