Recreate an air raid shelter in your classroom out of paper, textbooks and blue tact men! Nothing like crushing some lovingly made blue tact people as a way to engage students in a lesson. Fold two sheets of A4 paper lengthways once then crossways once to make an L shape. Staple together for added strength. Repeat. These are the shelter walls.Place the exercise books on top of the walls. (represents weight ratio of concrete roof on brick walls) Knock away the paper with the side of one hand, right through the end or side of the shelter.