October 22, 2008

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Teacher Notes

Subject: Maths

Topic: Number operations

Title: Addition of Integers

Year Group(s): 7, 8 and 9 Curriculum-related themes: Non-specific

Intended learning outcome(s)· Learn the rules for adding integers· Gain practice adding integers

Recommended usage: Introduction / main activity

October 22, 2008

Addition of Integers

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +10

Submitted by: Gerry-Lynn BorysRed Deer Catholic Regional Division: St.Patrick's Community School

Windows(R) operating system and Mac OS X operating system software

October 22, 2008

means + 1

means -1

You can use algebra tiles to add integers.

October 22, 2008

This is the same as saying (+3) + (-2) = +1

This is the same as saying(+2) + (-4) = -2

Example

=+1 = -2

October 22, 2008

The zero principle states that when you add two opposites, their sum is equal to zero.

Zero principle

(+1) + (-1) = 0

October 22, 2008

left with +1

left with -2

So, in our two examples

=0 =0 =0 =0

October 22, 2008

Use the yellow (positive) tiles and red (negative)tiles to add each pair of integers, then write the addition sentence for each.

(+5) + (-4)

(+3) + (-7)

(-4) + (-3)

October 22, 2008

Answers

(+5) + (-4)

(+3) + (-7)

(-4) + (-3)

October 22, 2008

You can also use a number line to add integers.

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +10

(+3) + (-2) Start at +3 and move back 2 spaces

+ sign means move forward or to the right of zero - sign means move back or to the left of zero

October 22, 2008

Solve the following questions using the number line.

(-3) + (-2)

(+5 ) + (-6)

(-7) + (+4)

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +10

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +10

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +10

October 22, 2008

Answers

(-3) + (-2)

(+5 ) + (-6)

(-7) + (+4)

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +10

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +10

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +10

October 22, 2008

You can also add integers algebraically.

Simply ignore the addition sign and do what the sign on the second integer tells you to do.

Example (+4) + (-5)

Ignore the addition sign and this question becomes

4 - 5 = -1

October 22, 2008

October 22, 2008

October 22, 2008

October 22, 2008

(+4) + (-3)= _____

(-3) + (+6)= _____

(+5) + (+2)= _____

(-2) + (-5) = _____

(-4) + (+2)= _____

+1

+3

+7

-7

-2