Subtracting Integers

Unit 3

Warm-Up

»In Colorado the temperature was -2 °F in the morning. If the temperature dropped 7°F, what is the temperature now?

Lesson Objective

»The student will be able to: ˃Subtract integers.˃Represent integer

subtraction using models.

Subtracting Integers Using Counters

» Negative- RED» Positive- YELLOW» Zero Pair˃ A number and its opposite˃ Have a sum of zero˃ Turn and Talk

+-

Using CountersZERO PAIRS

5 - 3 =

+++++

Using CountersZERO PAIRS

5 - 3 = 2

++

Using CountersZERO PAIRS

3 - 5 =

+ + +

Bring in zero pairs

Using CountersZERO PAIRS

3 - 5 = -2

Using CountersZERO PAIRS

3 – (-5) =

+ + +-- -

+ + +

--

+ +

Bring in zero pairsBring in zero pairs

Using CountersZERO PAIRS

3 – (-5) =

+ + +-- -

+ + + + +

8

Modeling Activity

A B

Discussion

» How did the models help you subtract integers?

»What rules or patterns did you notice about subtracting integers?

» You can always draw your own counters if you do not have counters available

Subtracting Integers

»RULE˃Keep it, Change it, Change it˃Then follow addition rules