Lesson 9: 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

• Reflect Points Across Axes — Flip a point over an axis, keeping the same distance.
• Reflection — A flip of a shape across a line.
• x-axis — The number line that goes left to right.
• y-axis — The number line that goes up and down.
• Symmetry — When both sides of a line match.
• Integer — A whole number or its opposite, like 2 and −2.
• Perpendicular — Lines that meet at a square corner (90°).

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 (4, -6) over the y-axis?

Check your answer

(-4, -6)

Reflecting over the y-axis changes the sign of the x-coordinate. x goes from 4 to -4, and y stays -6. The reflection is (-4, -6).

Sentence starter

I know ___ because ___.

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