Grade 6 · Math · Unit 10 of 13
Symmetry and Congruence
Mirror lines, turns and matching shapes
What your child practises
Lines of symmetry in regular and irregular polygons, rotational symmetry and turn angles, congruent shapes, which moves keep a shape congruent, and tiling a surface.
Alberta Curriculum learning outcome: 6G1.1, 6G1.2 · reflection and rotational symmetry, regular polygons, congruent shapes and tessellations
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
What is the smallest turn, in degrees, that makes a regular pentagon look the same?
- 90°
- 72°
- 180°
- 30°
Show answer
72°
Hint: Divide a full turn, 360°, by the number of matching positions.
Question 2
How many lines of symmetry does a equilateral triangle have?
- 3
- 0
- 1
Show answer
3
Hint: A line of symmetry folds the shape so both halves match exactly.
Question 3
Which capital letter has a vertical line of symmetry?
- U
- J
- E
- F
Show answer
U
Hint: Fold the letter down the middle from top to bottom. Do the sides match?
Question 4
Which move does NOT give a congruent image?
- Turning it (rotation)
- Flipping it (reflection)
- Enlarging it (dilation)
- Sliding it (translation)
Show answer
Enlarging it (dilation)
Hint: Slides, flips and turns keep size and shape the same.
Question 5
A rectangle that is not a square has rotational symmetry. How many times does it match itself in one full turn?
- 7
- 2
- 3
Show answer
2
Hint: Count the number of turns that make the shape look the same until you are back at the start.
Question 6
How many lines of symmetry does a rectangle that is not a square have?
- 4
- 0
- 2
Show answer
2
Hint: A line of symmetry folds the shape so both halves match exactly.