7th Grade Math

Add and Subtract Integers

PART A BCD

Multi-Part

Lesson 2

Get ConnectED

GLE 0706.2.1

Extend understandings

of addition, subtraction,

multiplication and division

to integers. SPI 0706.2.5

Solve contextual problems

that involve operations with

integers. Also addresses

GLE 0706.1.3, GLE 0706.1.8,

GLE 0706.2.2.

86 Integers

Main Idea

Model addition of

integers.

Vocabulary

zero pair

Add Integers

FOOTBALL In football, forward progress is represented by a

positive integer. Losing yardage is represented by a negative integer.

On the first play a team loses 5 yards and on the second play they

lose 2 yards. What is the team’s total yardage on the two plays?

• 9 - 8 - 7 - 6 - 5 - 4 - 3 - 2 - 1 0 1 2
  
  
  • 2 - 5
  
  
  
  

What do you need to find? the total yardage on the two plays

Use counters to find the total yardage.

Combine a set of 5 negative - -

counters and a set of

2 negative counters.

Find the total number of

counters.

So, - 5 + (-2) = -7. The football team lost 7 yards on the

two plays.

The following two properties are important when modeling

operations with integers.

• When one positive counter is paired with one negative counter,
  the result is called a zero pair. The value of a zero pair is 0.

(^) - +

• You can add or remove zero pairs from a mat because adding or
  removing zero does not change the value of the counters on
  the mat.

iti

V

z

086_098_C2L2_895130.indd 86 12/29/09 4:00 PM