Group: Geometry • Class II • Time: 20 minutes
By H. Dyke
The Parents’ Review, 1906, pp. 497-498
I. To teach the properties of parallel lines.
II. To cultivate the habit of accurate work.
III. To give training in neatness.
IV. To show Janet the practical use of geometry.
Step I.—Ask Janet to draw any two lines on the board and produce them till they meet. Let her draw two lines which will not meet if produced.
Step II.—Give the definition. Lines which, when produced, will never meet are called parallel lines. Ask her to name any pairs of parallel lines in the room.
Step III.—Show Janet how to draw parallel lines, using a set square and ruler.
Step IV.—Let Janet practise this and then draw lines through the pairs of parallel lines, thus—Ask her to measure all the angles and discover any relation between them, viz., the angles marked 1 are always equal, also those marked 2, and those marked three always make together two right-angles.
Step V.—Ask her to cut out such a figure in paper and fit the alternate angles upon one another to show that they are equal.
Step VI.—Ask her what practical use she could make of this knowledge, e.g., in cardboard sloyd she might test squares and rectangles by measuring the alternate angles.
Step VII.—Summarise by asking Janet to say, without actual measurement, which of the pairs of lines drawn on the board are parallel and pointing out the pairs of equal angles.