The Design of Geometry Teaching: Learning from the Geometry Textbooks of Godfrey and Siddons

Deciding how to teach geometry remains a demanding task with one of major arguments being about how to combine the intuitive and deductive aspects of geometry into an effective teaching design. In order to try to obtain an insight into tackling this issue, this paper reports an analysis of innovative geometry textbooks which were published in the early part of the 20th Century, a time when significant efforts were being made to improve the teaching and learning of geometry. The analysis suggests that the notion of the ‘geometrical eye’, the ability to see geometrical properties detach themselves from a figure, might be a potent tool for building effectively on geometrical intuition so as to provide a bridge into deductive geometry.