Math 20-2

Chapter 8 Proportional Reasoning

Lesson 8.3   Scale Diagrams

GOAL

The goal of this lesson is stated at the top of page 466 in your textbook, and is also written below.
Keep this in mind as you work through the lesson material.

Understand and use scale diagrams involving 2-D shapes.

Explore...

Try to answer the question in the sidebar on page 466.

You might also want to think about how you might do the exploration using THIS special grid paper.

Watch

Video Tutorial

Video Tutorial   Scale Diagrams   (Explore A)

Video Tutorial  using a polar grid     (Explore C)

Steps to follow

•	What does N 20°E mean?   
	Which direction would that be?  
	How does this relate to the compass rose?

•	How far will this plane travel in 2.5 hours?

•	What scale  will you use for the diagram?

Investigate the Math

Investigate an idea or problem, with a partner if possible.
The investigation provides the background for the ideas presented in the lesson.

TEXT Pages 466 - 467

Read/Work through the Investigate section on Pages 466-467 in your textbook.

Go through this material,  AS BEST YOU CAN,  before you view the video tutorials that follow.

How can you use a scale diagram of this room, on an 8.5 in. by 11 in. sheet of paper, to determine where to place these pieces of furniture?

Video Tutorial

Reflect G  click for the answer

If you use a scale of 1/16,  all the measurements end up being in increments of a quarter of an inch, making it easy and convenient to draw the diagram

Apply the Math  (Examples)

Examples will give you TOOLS for solving problems, and also show you that there may be different ways to approach a question.

YOUR TURN gives YOU the chance to try to do a problem ON YOUR OWN,  using the examples as models.

Example 1  Drawing a 2-D scale diagram that requires a reduction

TEXT Pages 467 - 468

Work through Example 1 on Pages 467 - 468 in your textbook.

Watch

Video Tutorial

Your Turn

Eric used a scale factor of (1/500)  which is 0.002
A scale factor of 0.01   is FIVE TIMES larger,  so Joe’s diagram would be 5 times larger than Eric’s.

Example 2  Drawing a 2-D scale diagram that requires an enlargement

TEXT Pages 468 - 469

Work through Example 2 on Pages 468 - 469 in your textbook.

Watch

Video Tutorial

Your Turn

Use the Video Tutorial for help, or to check your work, BUT... you should do your best to do this question ON YOUR OWN FIRST!

Video Tutorial

Example 3  Determining scale factor

TEXT Page 470

Work through Example 3 on Page 470 in your textbook.

Watch

Video Tutorial

Your Turn

I answered this when I did the example.

In Summary

Key Ideas and Need to Know 
Presents and summarizes  the main new concepts of the lesson

•	Carefully read through each of the bullet points in this section.

•	If you are unclear about any of these ideas,  ASK YOUR TEACHER FOR HELP!

Practice Problems

Doing Practice Problems

Practice problems reinforce the math presented in this lesson.

•	Work through the practice problems for this lesson.
	These problems are for practice, you don’t need to hand them in!
	(your teacher may assign specific questions for you to complete)

•	Use the answers in the back of the book to CHECK YOUR WORK!

•	If you make a mistake, TRY TO FIX IT!

•	If you need help or want more information, view the video solutions provided.

•	If you still need more help,  CONTACT YOUR TEACHER!

Types of Practice Problems

Check Your Understanding questions require basic understanding of the ideas of the  lesson.

Practising questions will require you to dig deeper for a solution.

Closing  A summary question that often asks YOU to explain ideas in your own words.

Extending questions offer enrichment and extension.

Notes

Question 7,    I didn’t do a video for this one.

Question 10,    I didn’t do a video for this one.
A great question, but straight forward.
You can check measurements and the resulting diagram with the answer in the back of the book.

Question 12,    I didn’t do a video for this one.
A great question, you will need to measure the actual diagram in your textbook and use the scale to find the real life distances.

Question 16,    I didn’t do a video for this one.

Question 19,    I didn’t do a video for this one.

Question 20,    I didn’t do a video for this one.
A great question, but well beyond the scope of this course!

Video Solution Links

Check your work for every problem you do!
If you make a mistake,  try to fix it!
Use the video solutions for more information.
If a problem still doesn’t make sense, ASK YOUR TEACHER FOR HELP!

({{"Question 1", "Question 2", "Question 3", "Question 4", "Question 5"}, {"Question 6",  , "Question 8", "Question 9",  }, {"Question 11",  , "Question 13", "Question 14", "Question 15"}, { , "Question 17", "Question 18",   ,  }})