In this hands-on activity, learners use heat to shrink samples of polystyrene plastic (#6 recycle code). Learners compare the size and shape of the plastic pieces before and after shrinking. They also compare the differences in the way the two plastics items, a tray and a cup, shrink. Due to the way they are manufactured, the cup only shrinks in one dimension, while the tray shrinks in two dimensions - find out why! Activity requires adult supervision if used with younger learners, due to use of hot plate. A great introduction to industrial chemistry.