New
New
Year 7

# Introduction to reflections

I can understand the nature of reflections and appreciate what changes and what is invariant

New
New
Year 7

# Introduction to reflections

I can understand the nature of reflections and appreciate what changes and what is invariant

## Lesson details

### Key learning points

1. The length of the lines do not change when reflected.
2. The angles inside an object do not change when reflected.
3. When an object is reflected, its image is congruent.

### Common misconception

Just because the sense has changed, it doesn't mean a reflection has occurred.

If an image has a different sense to its object, there has definitely been a reflection - the line of reflection may be at an obscure angle.

### Keywords

• Reflection - A reflection of a shape is the mirror image of the shape. An object is reflected when it is flipped over a fixed line.

• Sense - The sense of an object is the direction of the orientation of the object.

To keep consistent with all Oak objects and images, green and purple are used. Students may question whether the sense has changed if the colour of the image is different - this is not the case; focus on only the shape and any words inside the shape.
Teacher tip

### Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

## Starter quiz

### 6 Questions

Q1.
When a vertex is labelled M$$^{\prime}$$, it means the __________ of M.
object
sense
centre of rotation
line of reflection
Q2.
Which point on the image is corresponding to vertex A on the object?
b
d
Q3.
A transformation is a process that may change the size, orientation, or __________ of a shape.
Q4.
In which of these images is the orientation invariant when compared to its object?
image 1
image 2
image 4
Q5.
In which of these images has the direction of the orientation reversed when compared to its object - where the direction of ABCD on the object is clockwise?
image 1
image 3
image 4
Q6.
Which property may not be invariant when an object is rotated?
length of a side
size of an angle
sense

## Exit quiz

### 6 Questions

Q1.
Which of these sentences uses the word "sense" correctly?
Correct answer: The sense of a word stays the same after translation because I can still read it
The sense of a word changes after rotation because it is harder to read
Correct answer: The sense of a word changes if its letters look they've been written backwards
The sense of a word stays the same after reflection because I can figure it out
Q2.
In which of these images has the sense changed compared to the object?
image 2
image 3
image 5
Q3.
Which of these transformations change sense?
translation
rotation