Grade 8 · Math · Unit 12 of 14
Tessellations & Transformations
Slides, flips, turns and dilations
What your child practises
Why some shapes tessellate, naming the transformations in a tiling, and finding the image of a point after a translation, reflection, rotation or dilation on a coordinate grid.
Prince Edward Island Curriculum curriculum outcome: Shape and Space · tessellations and transformations of shapes
How we explain it
Children can open this short lesson before they practise.
- A translation slides, a reflection flips, a rotation turns and a dilation resizes.
- A tessellation covers a surface with copies of a shape with no gaps.
- On a grid, a translation adds to or subtracts from x and y.
Example: Translate (1, 2) right 3 and down 4. Right 3: x = 1 + 3 = 4. Down 4: y = 2 − 4 = −2. Answer: (4, −2)
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
Point A(3, 6) is rotated 90° counterclockwise about the origin. What are the coordinates of A′?
- (−6, 3)
- (−3, 6)
- (3, −6)
- (−3, −6)
(−6, 3)
Hint: Turn the grid in your mind. A 180° turn changes both signs. A 90° turn swaps the coordinates and changes one sign.
Question 2
Which rule describes a reflection in the x-axis?
- (x, y) → (x, −y)
- (x, y) → (y, x)
- (x, y) → (−x, y)
- (x, y) → (−x, −y)
(x, y) → (x, −y)
Hint: A reflection in the x-axis keeps the left-right position and flips up and down.
Question 3
Point A(−2, −4) is reflected in the y-axis. What are the coordinates of A′?
- (2, 4)
- (−2, 4)
- (2, −4)
- (−4, −2)
(2, −4)
Hint: A reflection in the y-axis flips the point left or right: the x-coordinate changes sign.
Question 4
In a tiling of triangles, every second triangle is a flipped copy of the one next to it across a shared side. Which transformation links them?
- reflection
- translation
- dilation
- a slide
reflection
Hint: A reflection flips a shape over a line, like a mirror.
Question 5
Squares tessellate because each angle is 90°. How many squares meet at each point?
- 8
- 3
- 6
- 4
4
Hint: Divide 360° by 90°.
Question 6
A rectangle is dilated by a scale factor of 4. A side that was 7 cm long is now how long, in centimetres?
answer boxcm
28 cm
Hint: Every length is multiplied by the scale factor.