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REPRESENTING SUBTRACTION A NUMBER
LINEAdd the opposite
Bell Ringer
What is subtraction?
Where we were…
Opposites, Zero Pairs, Additive Inverse
Commutative Property of Addition
Rules for Adding Integers…
Where we are…
Unit Plan Students will learn to…
Discuss strategies for adding integers.
Compare and contrast subtraction and addition of integers.
Strategies for Adding Integers
Number Line
Context Money Football Others?
Rules Adding like signs Adding opposite signs
Is p – q = p + (-q)
Explain
Group Activity
Write down the problem assigned to your group.
Solve using a number line. Compare with others in your group.
Compare with someone in your partner group.
Discuss the questions.
Model on a Number Line
Group 1: 8 – 3
Group 2: 7 – 13
Group 3: -15 - 6
Group 4: 8 + (-3)
Group 5: 7 + (-13)
Group 6: -15 + (-6)
Write the problem above your number line.
Compare with Other Group
GROUPS 1 and 4 2 and 5 3 and 6
Discussion Questions: How are your problems
similar? How are they different? What previous vocabulary is
used?
Model on a Number Line
Group 1: 8 – 3
Group 2: 7 – 13
Group 3: -15 - 6
Group 4: 8 + (-3)
Group 5: 7 + (-13)
Group 6: -15 + (-6)
Changing Subtraction to Addition
8 – 3 8 + (-3)
7 – 13 7 + (-13)
- 15 – 6 -15 + (-6)
- 2 – (-9)
- 2 + 9
Add the Opposite
Is p – q = p + (-q)
Explain
Subtraction Strategies
Use a number Line
Use context Money Football Others?
“Add the Opposite” and use rules for addition
Homework
Check homework
Quiz
Homework
Integer Investigation
SHOW ALL STEPS
Pick one of the strategies and use it… Pictures Number Line Rules Context
Exit Ticket
When would using a number line to model addition or subtraction of integers not be an efficient strategy?
1 minute – talk with your partner
2 minutes – Power Write
Bell Ringer
When would using a number line to solve addition or subtraction of integers not be an efficient strategy?
Where we were… Addition Strategies
Number line Context Rules
Same signs – add and keep the signs Opposite signs – subtract, keep sign of # w/
largest absolute value. Subtraction strategies
Number Line Context “add the opposite” and use rules for addition
Where we are…
Students will learn to…
Review the strategies used for adding and subtracting integers.
Practice
On Jeopardy, Jill answered one question correctly for 400. She then answered two questions incorrectly, one for 100 and the other for 200.
Write an ADDITION expression to represent the situation.
Write a SUBTRACTION expression to represent the situation.
How many total points did Jill have?
Practice On Jeopardy, Jill answered one question
correctly for 400. She then answered two questions incorrectly, one for 100 and the other for 200.
Write an ADDITION expression to represent the situation. 400 + (-100) + (-200)
Write a SUBTRACTION expression to represent the situation. 400 – 100 - 200
How many total points did Jill have? 100
Practice
A deep sea diver saw his jelly fish at 12 feet below sea level. He dove down another 20 feet before he finally saw another jelly fish.
Write an ADDITION expression that shows this scenario.
Write a SUBTRACTION expression to represent the situation.
What was the total depth of the diver?
Practice A deep sea diver saw his jelly fish at 12
feet below sea level. He dove down another 20 feet before he finally saw another jelly fish.
Write an ADDITION expression that shows this scenario. -12 + (-20)
Write a SUBTRACTION expression to represent the situation. -12 - 20
What was the total depth of the diver? -32 ft
Practice
John owed his mom $40 for a new pair of shoes. He then borrowed $15 for a new DVD.
Write a SUBTRACTION expression that shows this scenario.
How much money does John owe?
Practice
John owed his mom $40 for a new pair of shoes. He then borrowed $15 for a new DVD.
Write a SUBTRACTION expression that shows this scenario.
-40 – 15 -40 + (-15)
How much money does John owe? -$55
Homework
Write an expression for each problem.
Solve any way you choose.
Label your answer.
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