Transformations on a Grid
Identify, describe, and represent the position of a shape following a reflection or translation using appropriate language; know that the shape has not changed
What a learner can do afterwards
- Reflect a triangle in a vertical mirror line on a coordinate grid and state the new coordinates
- Translate a shape 3 units right and 2 units up and describe the movement
- Explain that a reflected/translated shape is congruent to the original
The lesson
You already know how to flip a shape over a line and how to slide it across a grid. Now you will do both of these on a coordinate grid, and describe the shape's new position using coordinates.
Triangle ABC has corners at (2, 1), (5, 1), and (3, 4). Reflect it in the vertical line x = 0. Each y-coordinate stays the same, but each x-coordinate flips sign: A' (-2, 1), B' (-5, 1), C' (-3, 4).
A square's corner starts at (1, 2). It slides 3 units right and 2 units up. Add 3 to the x-coordinate and 2 to the y-coordinate: (1 + 3, 2 + 2) = (4, 4).
After a reflection or a translation, the shape is congruent to the original. That means it is exactly the same size, with the same angles, just in a new spot on the grid.
Reflecting or translating a shape only changes its position on the grid. The shape itself, its size and its angles, never change.
Watch it
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.