A bell signalling a period change is ringing as MS FRASER enters from the prep room carrying a large tray which she puts down on the side bench next to the stack of metre rulers. The tray contains a number of spring balances, lengths of string, large wooden blocks, single pulleys, 200 g masses, various smaller masses and sticks of chalk. She then moves to a position behind the demonstration bench. At the same time, around thirty students-a mixture of boys and girls aged around 13 to 14 years-are entering from the corridor. All of the students are wearing at least one item of what is obviously school uniform, although it is equally obvious that the school does not enforce a strict uniform policy. The students are ethnically diverse-Anglo/ European, Mediterranean/Middle Eastern, Asian-and are talking noisily among themselves as they take their seats. Among the students are NATALIE, IRENA, MARK and a Japanese boy DASUKE.