Lesson: Subtract Integers Using Models (Counters/Numberline)
Lesson Objective
Lesson Plan
Standard 

· 6NSO.C9 Know integer subtraction is the inverse of integer addition; use the number line to model addition and subtraction of integers and add and subtract integers 

Aim/Objective: 
Key Points 
Subtract integers using counters and models 
· To subtract a positive number on the number line, move left · To subtract a negative number on the number line, move right · A negative and positive unit together equal one (a black counter and white counter together equal one) 
Assessment: 

Directions: Use counters or a number line to solve the following subtraction problems. 1. 8 – ^{–}7 2. 3 – 9 3. 7 – (^{–}9)
The number line below shows the number sentence: 4 + 6 = 2 Write a subtraction number sentence for the same number line.




Warm Up: (5 mins) · Review addition of positive and negative integers § 16 + 8 § 1 + 7 § 3 + 8 § 4 + 10 § 5 + 9 § 2 + 9
Opening: (5 mins) · Today we are going to explore subtract with positive and negative integers · Usually when we think of subtraction, we think about taking away · Today when we think of subtraction, I want us to add thinking about doing the opposite of addition. · We can use this line of thinking because subtraction and addition are inverse operations – they are the opposite of one another. Intro/Direct Instruction: (10 mins) · Model with students using the number line to subtract integers · Tell students that the first number tells us where to start on the number. The operation and the second number tell us what direction to go in. · Walk through an example  when adding 2 to a number we would move 2 units to the left  however since we are subtracting negative 2 we need to move two units to the right · Explain that when we subtract a positive we move the LEFT · When we subtract a negative we move the RIGHT · Walk students through using counters to subtract. Remind them that subtraction in some cases is a way to describe taking away. Show a model with two positive numbers (9 – 5) in this case you are taking away five from nine · However, sometimes it is not this easy. Let’s look at the following example: · Otis earned $5 babysitting. He owes Latoya $7. · To set up this problem, we will start with the 5 dollars Otis has – we represent that with 5 white counters. Now we need to take away $7 or 7 white tiles. However, we only have the five white counters so it’s not possible to take away 7. In order for us to take away 7 white counters, we need to add 2 more white counters. In order to add the two white counters we have to add 2 black counters. We can do this because a white counter and a black counter together equal 0. Now we can take away seven white counters and we are left with two black counters – meaning our final answer is two black counters or two negatives (2) Guided Practice: (10mins) · Allow students to practice with number lines and with counter examples – walking them through each step? · For number line problems: o Ask: where do we start o Which way are we going to move? o How many spaces are we going to move? · For counters: o What does my starting board look like? (How many counters, what color) o How many are we taking away? o Do we have enough? (Yes – take them away and solve; No – next question) o How many more do I need in order to take that amount away? o What counters do I need to add to the board (you have to add the same number of white as black or vice versa)
Independent Practice: (15 mins) · Students complete worksheet – teacher circulates to monitor understanding/practice – or pull a small group of students who struggled during the guided practice
Closing · Exit Ticket · Describe to your neighbor – how do you subtract with a number line? Switch – how do you subtract with counters
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Lesson Resources
Notes Subtract Integers with Models Notes 
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Notes 6 Subtract With Models 
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Notes 6 Subtract With Models 
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Exit Ticket Subtract Integers models 
1,146

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