Children. Not if you shut your eye.
Teacher. Can you break glass?
Children. We'll try (one child breaks a window).
Teacher. Then glass is brittle?
Children. Rather.
Teacher. Will the shutter break?
Children. We are not going to try that.
Teacher. (Striking the shutter violently). Now, what have I done?
Children. Made a great noise, and hurt your own knuckles.
Teacher. What is wax?