Math 20-2

Chapter 1 Inductive and Deductive Reasoning

Lesson 1.5  Proofs That Are Not Valid

GOAL

The goal of this lesson is stated at the top of page 36 in your textbook, and is also written below.
Keep this in mind as you work through the lesson material.

Identify errors in proofs

Explore...

Try to answer the question in the sidebar on page 36.

Watch

Video Tutorial

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 Page 36

Read/Work through the Investigate section on Page 36 in your textbook.

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

Introduction

Video Tutorial

?  How was it possible for 64 to equal 65?

If you can,  actually doing this investigation would really help!
I will use my computer drawing program to illustrate what is happening here.

Video Tutorial

Reflecting

I covered these questions in the video from the previous section

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  Use reasoning to determine the validity of an argument

TEXT Page 37

Work through Example 1 on Page 37 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 2  Use reasoning to determine the validity of a proof

TEXT Pages 37 - 38

Work through Example 2 on Pages 37 - 38 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  Use reasoning to determine the validity of a proof

TEXT Page 39

Work through Example 3 on Page 39 in your textbook.

Watch

Video Tutorial

Your Turn

I covered this in the previous video.

Example 4  Use reasoning to determine the validity of a proof

TEXT Page 40

Work through Example 4 on Page 40 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 5  Use reasoning to determine the validity of a proof

TEXT Page 41

Work through Example 5 on Page 41 in your textbook.

Watch

Video Tutorial

Your Turn

I didn’t do a video for this question.

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

Question 9,    I didn’t do a video for this one.
Here is a video that gives some information about this.
LINK
https://youtu.be/XlQOipIVFPk
Here is another one  (if you do a search for Moebius strip, you will get many hits...)
LINK
https://youtu.be/f-19NLKxNUc

If you can try it yourself, even better.
It’s a pretty amazing thing.

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 7",  ,  , "Question 10"}})