Lesson

A reflection occurs when we flip an object or shape across a line. Like a mirror, the object is exactly the same size but everything is in the opposite position. In other words, what was on the left will now be on the right and vice versa.

Have a play with the applet below. You can change the shape, the position of the shape and the direction of the line.

As you play, notice how:

- every point on the object or shape has a matching point on the flipped image
- both shapes are the same distance from the reflection line

Which picture shows a reflection?

Think: Which picture looks like its been flipped- A or B?

Do: In (B), the picture is exactly the same. It has just been slid down. This means it's a translation.

In (A), the alien's spaceship has been flipped upside down! So this is the reflection.

This picture is an example of a:

Translation (slide)

AReflection (flip)

BRotation (turn)

CMagnification

DTranslation (slide)

AReflection (flip)

BRotation (turn)

CMagnification

D

Which image below represents the reflection for the following shape about the vertical mirror line?

- ABCABC

Which image below represents the reflection for the following shape about the vertical mirror line?

- ABCDABCD

Predict and communicate the results of translations, refl ections, and rotations on plane shapes.