Using Negative and Absolute Numbers

Using Negative and Absolute Numbers

Construct and Critique Arguments

Opening

Construct and Critique Arguments

The absolute value of a number is the distance a number is from 0 on a number line. The symbol |a| is used to indicate the absolute value of a.

Watch the video.

  • What did Carlos think absolute value was at the beginning of the video?
  • What did Jan suggest doing to help them think about absolute value?
  • What argument did Carlos use to say that the absolute value of 12 cannot be –12?
  • What model did Jan and Carlos use to help them understand absolute value?
  • What would Carlos have said the absolute value of 8 is at the beginning of the video? What would Carlos have said the absolute value of 8 is at the end of the video?

 

Math Mission

Opening

Understand when to use the absolute value of a number.

Temperatures in Barrow, Alaska

Work Time

Temperatures in Barrow, Alaska

The table shows some low temperatures recorded in Barrow, Alaska, during a 12-month period. Use the table to answer these questions.

  • What is the coldest temperature?
  • How far below 0°F is the coldest temperature?
  • What is the difference between the lowest and highest temperatures, in degrees? Explain how you know.
  • When did you use a negative number and when did you use the absolute value of a number?

Ask yourself:

  • Represent the temperatures on a number line. Where is the coldest temperature?
  • Can you represent distance using a negative number or using an absolute value?
  • How many degrees above 0°F is the highest temperature?
  • How many degrees below 0°F is the lowest temperature?
  • How many degrees are between the highest and lowest temperatures?

Prepare a Presentation

Work Time

Prepare a Presentation

  • Explain when you use a negative number and when you use the absolute value.
  • Demonstrate how to take the absolute value of a number.

Challenge Problem

  • Create a story problem that has a negative answer.
  • Create a story problem that includes a negative value but has a positive answer.

Make Connections

Performance Task

Ways of Thinking: Make Connections

Take notes about how to determine the absolute value of a number and when to use the absolute value of a number.

Hint:

As students present, ask questions such as:

  • How can a number line be used to solve the problem?
  • In what types of situations is it best to use the absolute value of a number?
  • In what types of situations is it best to use a negative number?

Absolute Value

Formative Assessment

Summary of the Math: Absolute Value

Write a summary of what you learned about absolute value.

Check your summary.

  • Do you include a definition of absolute value?
  • Do you explain how to find the absolute value of a number on a number line?
  • Do you talk about when to use the absolute value?

Reflect On Your Work

Work Time

Reflection

Write a reflection about the ideas discussed in class today. Use the sentence starter below if you find it to be helpful.

When I look at the absolute value of a number and the opposite of a number, I see these connections …