Q. What is this. A. A trapezoid. Q. How many sides has it? A. Four sides and four angles, it has only two of its angles equal, which are opposite to each other.
Tetragon.
Q. What do we call these figures that have four sides. A. Tetragons, tetra meaning four. Q. Are they called by another name? A. Yes, they are called quadrilaterals, or quadrangles. Q. How many regular tetragons are among those we have mentioned? A. One, that is the square, all the others are irregular tetragons, because their sides and angles are not all equal. Q. By what name would you call the whole of the figures on this board? A. Polygons; those that have their sides and angles equal we would call regular polygons. Q. What would you call those angles whose sides were not equal? A. Irregular polygons, and the smallest number of sides a polygon can have is three, and the number of corners are always equal to the number of sides.
Ellipse or Oval.
Q. What is this? A. An ellipse or an oval. Q. What shape is the top or crown of my bat? A. Circular. Q. What shape is that part which comes on my forehead and the back part of my head? A. Oval.
The other polygons are taught the children in rotation, in the same simple manner, all tending to please and edify them.
The following is sung:—
Horizontal, perpendicular,
Horizontal, perpendicular,
Parallel, parallel,
Parallel, lines,
Diverging, converging, diverging lines,
Diverging, converging, diverging lines.
Spreading wider, or expansion,
Drawing nearer, or contraction,
Falling, rising,
Slanting, crossing,
Convex, concave, curved lines,
Convex, concave, curved lines.
Here's a wave line, there's an angle,
Here's a wave line, there's an angle;
An ellipsis,
Or an oval,
A semicircle half way round,
Then a circle wheeling round.