This section is from the book "Amateur Work Magazine Vol6". Also available from Amazon: Amateur Work.
Richard Inwards, a correspondent of the "English Mechanic," contributes to that journal some particulars of a suggestive model designed for the improvement of the student's knowledge of practical geometry. He says that a new technical school is to be furnished with such models, and that the use of these is not to prove but to exhibit the facts and that furthermore, if the students are set to work on triangles of different proportions they must be dull indeed if they do not absorb the facts.
It will be seen that the triangle is cut up and the parts hinged together to show that triangles can be folded to make two parallelograms. The model is expected to impress the following facts upon the pupil: That all the angles of a triangle make 180 degrees, or two right angles when added together; that any triangle can be divided into two rectangles; that any triangle can be measured by multiplying its base by half its height; "any boy can understand the measurement of a rectangle," pointedly remarks Mr. Inwards, and that any triangle can be divided into two right-angled triangles.