Lesson 7: Reflect Points Across Axes6.NOS.7

I can…

I can reflect points across the x-axis and y-axis on the coordinate plane.

Key words

• Reflection — A flipped, mirror image across a line.
• x-axis — The line that goes across the grid. Flipping over it changes the y sign.
• y-axis — The line that goes up the grid. Flipping over it changes the x sign.
• Symmetry — When a shape looks the same on both sides of a line.
• Integer — Whole numbers and their opposites, like -2, -1, 0, 1, 2.

Steps

1. I will reflect (3, 2) over the y-axis.
2. The y-axis is the vertical line, so the point flips left or right. That changes the x-coordinate.
3. The x changes sign: 3 becomes -3. The y stays the same: 2 stays 2.
4. So the reflection of (3, 2) over the y-axis is (-3, 2).

Try it

What is the reflection of (-5, 2) over the y-axis?

Check your answer

(5, 2)

Reflecting over the y-axis changes the sign of the x-coordinate. x goes from -5 to 5, and y stays 2. The reflection is (5, 2).

Sentence starter

I know ___ because ___.

Goal: I can explain my work using the words reflection, x-axis, y-axis, and symmetry.