Provide enough wait-time for students to reflect when responding to inquiries. Provide emotionally supportive environments in the classroom encouraging reevaluation of conclusions. Prompt reviews of the learning situation, what is known, what is not yet known, and what has been learned.
Polyurethane is a fully reacted polymer in which every molecule bonds with another so it is chemically inert, which keeps it from oxidizing or leaching chemicals, theoretically extending tire life. Tires of the future?
Polyurethane combines the best properties of rubber and plastic, without the weaknesses inherent in plasticized vinyl films. Because it contains no plasticizers, it is not subject to the brittleness and other problems caused when they leach to the surface.