Watt Watchers of Texas: Texas is Too Good To Waste™

Activity: Comparing Plastics

Grade Level:

Activity Overview: Most items made of plastic are marked for recycling with a number 1 to 7. These numbers indicate what kind of plastic makes up the item. In this activity, students will use their knowledge of the numbers to categorize different plastics. You can also pair this activity with Hunt for Recycling and explain to students that some materials are more readily recyclable than others.

The plastic numbering system looks like this:

The symbols may or may not be labeled on the packaging. You can introduce the symbol to your students by printing or projecting the universal recycling symbol, which will appear on most products labeled for recycling.

Time: 15-20 minutes, depending on number of plastic items


Set out a collection of plastic items or examine the plastic items found in the Hunt for Recycling activity. Students should work individually to locate the recycling symbol and then determine what number is printed within it. If you do not have enough plastic materials for every student to have one, pair or group students to work together.

Then students should organize items along the classification of the type of plastic. All 7 (Other) plastics should be grouped together, and all 1 (polyethylene terephthalate) should be grouped together and so on. How many of each category are there? How many items overall?

Finally, students should use their knowledge of the number line and the magnitude of numbers to place items in numerical order. The activity becomes slightly more challenging if you do not have an item for each number. What number comes after 5 if no 6 is present in your collection?

Additional Resources

For more information on the different types of plastic and their recycling status, consult this article from Good Housekeeping.



Watt Watchers of Texas is a Partner Program of Smart Energy Education.
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