With these prefatory remarks I shall introduce a description of the method I have pursued, and a few examples of geometrical lessons.
We will suppose that the whole of the children are seated in the gallery, and that the teacher (provided with a brass instrument formed for the purpose, which is merely a series of joints like those to a counting-house candlestick, from which I borrowed the idea,[A] and which may be altered as required, in a moment,) points to a straight line, asking, What is this?
A.A straight line.

Q.Why did you not call it a crooked line?
A.Because it is not crooked, but straight.

Q.
What are these?
A.Curved lines.

Q.What do curved lines mean?
A.When they are bent or crooked.

Q.What are these?
A.Parallel straight lines.