Present the model. Teach here the triangular prism, and have the pupils, by measuring, see that the sides of the triangular ends are equal.

Exercise No. 11. - Draw on the board a square, construct within the square on one of its sides an equilateral triangle, by means of arcs with a pair of chalk dividers; and following the plan as with the oblong, have the pupils draw their diagram. Fold and sew the triangular prism, leaving one oblong face with loop for hanging.