Answer:
The rubber in your erasures.
The rubber bands in the braces of some students.
The plastic overhead transparencies the teacher uses.
The linoleum on some classroom floors.
The plastic coverings for the fluorescent lights overhead.
The synthetic fabrics in some of the shirts and pants worn.
The glasses that students and teachers wear, both lenses and temples.
The plastics in the cell phones that students are not supposed to have. Ditto for their iPods.
Some examples are: polycarbonate, polytetrafluoroethylene, polyvinylacetate, polysulphone, polythene, polytheneterephtalate, polyamide, polymetaacrylate and many others.
And your teachers pointy thing!!!