rushton's difference lesson | subtraction under the common core mathematics standards
DESCRIPTION
Introduce subtraction as the difference operation using money, height, and temperature as analogous metaphors. Then show a series of contrasting cases to explain why the signed integer rules for subtraction work. Recommend allowing students to use a number line to solidify their understanding with a visual representation.TRANSCRIPT
What’s the Difference?
vs$300 $20
$280 more
What’s the Difference?
vs $300$20
$280 less
What’s the Difference?
vs5’7” 5’2”
5 inches more
What’s the Difference?
vs103° 75°
28° more
What’s the Difference?
vs52° 75°
23° less
What’s the Difference?
vs52° -10°
62° more
What’s the Difference?
vs-2° -10°
8° more
What’s the Difference?
vs-43° -10°
33° less
What’s the Difference?
vs-21° 89°
110° less
What’s the Difference?
8 vs 3
5 more
What’s the Difference?
9 vs -5
14 more
What’s the Difference?
-13 vs 4
17 less
What’s the Difference?
12 - 7
5
“5 more”
What’s the Difference?
7 - 3
4
“4 more”
What’s the Difference?
-14 - 8
-22
“22 less”
What’s the Difference?
19 - (-4)
23
What’s the Difference?
-11 - 9
-20
What’s the Difference?
6 - 6
0
What’s the Difference?
10 - (-2)
12
What’s the Difference?
15 - 3
12
What’s the Difference?
-3 - 7
-10
What’s the Difference?
-3 - (-8)
5
What’s the Difference?
80 - 20
60
What’s the Difference?
-10 - 60
-70
What’s the Difference?
140 - 30
110
What’s the Difference?
80 - 35
45
What’s the Difference?
15 - (-25)
40
What’s the Difference?
90 - 30
60
What’s the Difference?
70 - 90
-20
What’s the Difference?
-140 - 35
-175
What’s the Difference?
175 - 90
85
What’s the Difference?
-170 - (-90)
-80
What’s the Difference?
35 - (-135)
170
What’s the Difference?