E2.3 Compare angles and determine their relative size by matching them and by measuring them using appropriate non-standard units.

Activity 1: Congruent Angles, or Not?


Look at the angles that are in the Cartesian plane below and answer the following questions without using a measuring tool.

  1. Are angles 1 and 5 congruent?
  2. How can you demonstrate this?
  3. Show the congruence of angles 2 and 3.
  4. Are the corresponding line segments that form angles 1 and 4 congruent? Explain your answer.
  5. Are angles 1 and 4 congruent? Explain your reasoning.

(Provide students with a transparency of the blank grid and erasable markers so they can trace certain angles, if necessary.)

A Cartesian plane quadrant with eleven columns and eleven rows. The columns are numbered on the horizontal axis, and the rows on the vertical axis. There are five corners scattered on the grid.

Source: translated from L'@telier - Ressources pédagogiques en ligne (atelier.on.ca).