Diagrams and images are used to explain the formation of waves, their swash and backwash. Constructive waves are flat and low with limited energy. This energy washes material up the beach to create a gentle beach. Destructive waves have much more energy and are higher. The backwash is very strong and removes material from the shore to create a steep beach.
Use as an introduction or recap on wave action. Students could create annotated diagrams or animations explaining the action of constructive and destructive waves. Give students a range of images of beaches that they have to classify by wave action, explaining the features that inform their decisions.