We see different examples of the materials used to make bridges, including stone, cast iron, brick and steel. Using plastic is a good idea; it is light, easy to build from, doesn't need cranes, and can be glued together. To give it strength, plastic can be reinforced with glass. This makes it strong and flexible enough to support its weight two times over.
Before watching this clip students could be asked to describe the characteristics of plastic and glass. They could create two mind maps or create a Venn diagram. They could then write a list of characteristics required by a material in order to be appropriate for use in a bridge. Do plastic or glass have any of these characteristics? After watching this clip and discovering that glass and plastic are appropriate for bridge building when used together, they could consider how the characteristics of these two materials have changed when combined.
Students could then be challenged to create their own small-scale bridges in the classroom using a range of materials such as paper, cardboard, moulding dough, aluminium foil or any other readily available materials. Students could work in small groups to test each material for the characteristics they have already identified as essential in bridge design, and then create their own bridge. These could then be tested by placing items on top. The strongest bridge could be declared the winner.