The geometers of ancient Greece invented a peculiar game for themselves, a game called Construction, whose objective is to draw various geometric figures of interest. We are permitted to use just two instruments: an unmarked straightedge (a ‘ruler’), and a compass. Using these, we can draw a straight line through any given pair of points, and we can draw a circle with any given point as centre and passing through any other given point. (Oh yes, we also possess a pencil and an eraser, please do not feel worried about that!)

Here is a simple way to bisect a given angle using the simplest and most familiar geometrical instrument: a ruler (see Figure 1). It works for any angle other than a straight angle (i.e., a 180 o angle).

The game featuring Ali, the ant helps the learners comprehend that adding positive integers makes the number bigger. It also gives them the practice of using a scale & number line.

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