1. Unit 1: Transformations Day 4: Dilations
Geometry
Unit 1: Transformations
Day 4: Dilations

2. Agenda
Warm-up
Homework Check
Quiz
Notes/Activity
Independent Practice

3. Warm-Up
Individually, rewrite your definitions WITHOUT using the vocabulary term. Then sketch a picture of each.
Isometry
Translation
Reflection
Rotation
e.g. Rotation is not “rotating an object”
Extra Question: What does the phrase “Be Kind, Please Rewind” mean

4. Homework Check
Solutions

5. Quiz
When finished, turn quiz over and remain quiet until all quizzes are picked up

6. In partners One at a time: 1 person close your eyes for 15 seconds.
The other person, watch their eyes as they open.
Write down what you notice.
Repeat with other person.

7. Dilation A dilation occurs when you resize a shape
It can get bigger or smaller.
but it still looks similar, meaning all angles stay the same and relative sizes are the same
Does a dilation have the property of isometry?
Can mention how a projector creates a dilation. This presentation is dilated so that those of you in the back of the room can see the words. It is enlarged for you to see.

8. All Dilations have a scale factor Scale Factor – how much a figure changes in size

10. What is the difference between an enlargement and a reduction?
The dilation is an enlargement if the scale factor is greater than 1.
The dilation is a reduction if the scale factor is between 0 and 1.

11. How do you go from A to A’ Does that work for B to B’ and C to C’?
Have students figure out that they multiply the ordered pair A by 2 to get the ordered pair A’. Have them verify this for point B to B’ and C to C’

12. Algebraic Rule for Dilations:
*c is called the scale factor
See if students can create this on their own.

13. If given a preimage and an image how do you find the scale factor?
A’ or A need to be either the x’s or the y’s of one coordinate, Unless the values are zero.

14. Example – Find the scale factor

15. Example – Find the scale factor

16. Independent Practice
Page #7-9, 18-23, 28-31, 38,39, 42

17. Exit Ticket
Come up with an example or a time you would see or use a dilation in the real world.

18. Homework
Dilation Worksheet