Teacher NotesThis method does not have students memorize the rule “reverse signs when multiply or divide by a negative”.

We are starting with reading a math problem.

Method: Solve the inequality like an equation. Then substitute the solution into the inequality and check a point on either side of the point to find the direction of the inequality sign.

The launch: The Text Messaging Plan Give students index cards with numbers of cell phone minutes. The first question has one solution– this is an equation. The last two questions are inequalities with ≤ ≥, respectively.

Good day for the mini whiteboards (one for each student)

Linear Inequalities Target 2I can solve inequalities in one variable.

What do you think is a solution to 3x + 1 ≥ 9

What do you think is a solution to 3x + 1 ≥ 9

Your teacher will give you a card with a number of

text messages.

LaunchLaunchLaunchLaunch

The Text Messaging PlanJohn’s mom gave him a cell phone. She said she would pay up to $50 each month for text messages. The plan charges $10 a month for 1,000 texts plus $0.10 per each texts over the included 1,000 texts.The card you have is the numberof texts John sent last month.Whose card has John’s mom payingthe full $50, but John paying nothing?

John’s mom gave him a cell phone. She said she would pay up to $50 each month for text messages. The plan charges $10 a month for 1,000 texts plus $0.10 per each text over the included 1,000 texts.The card you have is the numberof texts John sent last month.Whose card has John’s mom paying less than $50?

The Text Messaging Plan

John’s mom gave him a cell phone. She said she would pay up to $50 each month for text messages. The plan charges $10 a month for 1,000 texts plus $0.10 per each text over the included 1,000 texts.The card you have is the numberof texts John sent last month.Whose card has John paying his mom?

The Text Messaging Plan

People Number Line

Find your place along the number line.

Tape your card along the number line.

Inequalities

Write an inequality that describes the number of texts which would satisfy each statement:

1. John’s mom pays less than $50.2. John’s mom pays $50.3. John pays his mom some money.4. John’s mom pays $50 or less.

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Work with a Partner

Be prepared to share.

Edgar’s gift card

Read the problem.What is the story?

Edgar has an itunes gift card for $50.

• Songs cost $0.99• Music videos cost $1.99• CDs cost $14.99How many CDs can Edgar buy and not spend more than his gift card?

Edgar’s gift card

Read it again.What do you want to know?

Edgar has an etunes gift card for $50.

• Songs cost $0.99• Music videos cost $1.99• CDs cost $14.99How many CDs can Edgar buy and not spend more than his gift card?

Edgar’s gift card

Read it again. What do you know now that can helpyou solve the problem?Edgar has an etunes gift card for $50.

• Songs cost $0.99• Music videos cost $1.99• CDs cost $14.99How many CDs can Edgar buy and not spend more than his gift card?

Edgar’s gift card

Write an equation that can be used to solve the problem.

Define the variable you used.Edgar has an etunes gift card for $50.

• Songs cost $0.99• Music videos cost $1.99• CDs cost $14.99How many CDs can Edgar buy and not spend more than his gift card?

Edgar’s gift card

Write an inequality that can be used to solve the problem.

Define the variable you used.Edgar has an etunes gift card for $50.

• Songs cost $0.99• Music videos cost $1.99• CDs cost $14.99How many CDs can Edgar buy and not spend more than his gift card?

Edgar’s gift card

Find all solutions.Graph the solutions on a number line.

Edgar has an etunes gift card for $50.

• Songs cost $0.99• Music videos cost $1.99• CDs cost $14.99How many CDs can Edgar buy and not spend more than his gift card?

Time to share.

Work with a Partner

Be prepared to share.

High School Musical

Read the problem.What is the story?

Tickets to the musical are $9 for adults, $5 for students without ASB, and free to students with ASB, and children. The 124 students bought their tickets in advance. If only adults buy the rest of the tickets, how many adults would have to buy tickets for the school to sell more than $1,000 in tickets?

High School Musical

Read it again.What do you want to know?Tickets to the musical are $9 for adults, $5 for students without ASB, and free to students with ASB, and children. The 124 students bought their tickets in advance. If only adults buy the rest of the tickets, how many adults would have to buy tickets for the school to sell more than $1,000 in tickets?

High School MusicalRead it again. What do you know now that can helpyou solve the problem?Tickets to the musical are $9 for adults, $5 for students without ASB, and free to students with ASB, and children. The 124 students bought their tickets in advance. If only adults buy the rest of the tickets, how many adults would have to buy tickets for the school to sell more than $1,000 in tickets?

High School Musical

Write an equation that can be used to solve the problem.

Define the variable you used.Tickets to the musical are $9 for adults, $5 for students without ASB, and free to students with ASB, and children. The 124 students bought their tickets in advance. If only adults buy the rest of the tickets, how many adults would have to buy tickets for the school to sell more than $1,000 in tickets?

High School Musical

Write an inequality that can be used to solve the problem.

Define the variable you used.Tickets to the musical are $9 for adults, $5 for students without ASB, and free to students with ASB, and children. The 124 students bought their tickets in advance. If only adults buy the rest of the tickets, how many adults would have to buy tickets for the school to sell more than $1,000 in tickets?

High School MusicalFind all solutions.Graph the solutions on a number line.Tickets to the musical are $9 for adults, $5 for students without ASB, and free to students with ASB, and children. The 124 students bought their tickets in advance. If only adults buy the rest of the tickets, how many adults would have to buy tickets for the school to sell more than $1,000 in tickets?

Time to share.

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Team PracticeTeam Practice

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DebriefDebrief

• What are the steps for solving a story problem?

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5

3

12

4

Did you hit the target? I can solve inequalities in one variable.

Rate your understanding of the target from 1 to 5.

5 is a bullseye!

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PracticePractice

Practice 2.2 Write and Solve Inequalities

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Ticket Out

Ann earns $5.95 per hour working after school. He needs at least $215 for his holiday shopping. How many hours must he work to reach his goal?

[A] at least 37 hours [B] at least 35 hours [C] at least 36 hours [D] at least 38 hours

How did you make your choice?

How did you make your choice?