Attached is an activity sheet that gives the concepts and instructions for an easy, very fun, and relatively cheap polymer demonstration. It was written for a junior high level and can be easily tailored for any age. Credit should go to another UCSB outreach program called LEAPS
Everything is safe (and even technically edible), easy to clean, and involves everyday (for coastal kids!) materials that your students will be able to play with hands on and can even take home.
Here's the information of a Goleta based company that provides the starter materials for the project:seafarms