Dilations & Similar Figures Lesson, TEKS 8.3A

​Do your Warm-Up!

What is our TEKS?

TEKS 8.3A:

The student will generalize that the ratio of corresponding sides of similar shapes are proportional, including a shape and its dilation.

Dilations & Similar Figures, TEKS 8.3A(S)

It's time for our lesson . . .

​Dilations & Similar Figures

You can take notes in your journal or lined paper, but be sure to pay attention.

Open Ended

What is one thing that you learned from the video?

• Dilation means that the size of the figure will change. The figure will get LARGER or SMALLER.

• Dilations produce SIMILAR FIGURES - meaning same shape but different size.

Real Life Examples of Dilations

Multiple Choice

A dilation produces a similar figure

• True

• False

Multiple Choice

This symbol stands for ...

• is corresponding to

• is congruent to

• is similar to

Multiple Choice

What is true about the shape and size of similar figures?

• Same shape and same size

• Same shape and not the same size

• Different shape and same size

• Different shape and not the same size

Multiple Choice

What is true about the angles of similar figures?

• Corresponding angles are proportional.

• Complementary angles are proportional.

• Corresponding angles are congruent.

• Complementary angles are congruent.

Multiple Choice

What does congruent mean?

• Same shape, different size

• Not same shape, or size

• Same size, same shape

Multiple Choice

This symbol stands for ...

• similar

• congruent

• proportional

• corresponding

Corresponding Sides:

When you have figures that are enlarged or shrunk, you can find the scale factor by comparing corresponding sides.

Multiple Choice

What are matching sides of similar figures?

• Corresponding Sides

• Corresponding Angles

• Scale Factor

Multiple Choice

_{Line AB corresponds with what line?} 

• XZ

• XY

• YZ

• YX

Multiple Choice

Are the following similar? Why or why not?

• Yes

• No, the corresponding angles are not equal.

• No, the ratios of the corresponding sides are not equal.

​solving for a missing side length in a similar figure

​Find corresponding side lengths

​set up a proportion to solve

​

​4.5 = x

​7.5 5

Multiple Choice

Which proportion could be used to find side 'x'?

Pay attention as you work through the problems with the teacher.

Time for Guided Practice . . .

Dilations & Similar Figures, TEKS 8.3A (S)

Multiple Choice

I DO:

Solve for x.

• 2 ft

• 3 ft

• 4 ft

• 6 ft

Multiple Choice

WE DO:

Which proportion can be used to find 'x'?

Multiple Choice

YOU DO:

Which proportion can be used to find 'x'?

​​Use your journal, lined paper, or dry erase board to practice solving the Quizizz problems on your own. Do as many problems as you can until the timer rings.

Time for Independent Practice . . .

Dilations & Similar Figures, TEKS 8.3A(S)

Multiple Choice

Tell whether the two figures are similar. Explain your reasoning. (Hint: are they proportional?)

• Yes, similar because they are the same shape and side lengths are proportional.

• No, not similar because they are the same shape, but side lengths are not proportional.

• Yes, same shape

• No, different sizes

Multiple Choice

Which side length corresponds with EF?

• NO

• LM

• ML

• EH

Multiple Choice

Which proportion can be used to find side 'x'?

Multiple Choice

Which proportion is true?

Multiple Choice

Time for your Mastery Check:

It's time to assess your skills using a STAAR-related problem. Carefully select your answer to the next problem to test your knowledge. You will use this for your Self-Assessment.

Dilations & Similar Figures, TEKS 8.3A(S)

Multiple Choice

Which proportion is true?

• $$\frac{v}{w}=\frac{5}{4.38}$$

• $$\frac{v}{6}=\frac{4.2}{2.52}$$

• $$\frac{6}{w}=\frac{5}{7.3}$$

• $$\frac{v}{6}=\frac{7.3}{2.52}$$

Poll

Self-Assessment:

• I'm an expert. I got this! (I can teach this skill to others.)

• I'm a Practitioner. I can do this with more practice. (I can re-do this lesson through Google Classroom.)

• I'm a Novice. I need help learning this skill! (I can come to tutoring to get the help I need, or I can ask an Expert for help.)