1. Using Two Color Markers to Represent Integers Featuring the Marker Brothers + - © Mathmadics Model Addition and Subtraction of Integers using Physical Materials.

2. We can use colored markers to represent integers when solving problems. + - © Mathmadics

3. When solving problems with integers, it is critical to model exactly what the problem instructs you to do. + - © Mathmadics

4. In this lesson, the red marker will represent a positive number and the yellow marker will represent a negative number. + - © Mathmadics

5. Let’s Model 3, -2 and 1 3 -2 1

6. When you have the same amount of red markers as you do yellow, then these are called zero pairs. The model represents 3 zero pairs. -3 + 3 = 0 When using markers to model, be careful to write only the amount you see.

7. When you have zero pairs, draw a line through the positive and negative markers to cross them out. The model represents 3 zero pairs. -3 + 3 = 0 Use a / to cross out your zero pairs.

8. Things to use as Modeling Mat: 1. Sheet of typing paper or notebook paper 2. Small white board 3. Sheet of white card stock When solving addition or subtraction integer problems, use a modeling mat to model your problems on.

9. + Example 1: -2 + -3 = -5 When using markers to model, + means to add to the mat. Step 1: Model the first number. Step 2: The sign tells you to add -3. Step 3: Look at the set and record your answer.

10. Example 2: -2 - 1 = -3 When using markers to model, - means take away from the mat. Step 1: Model the first number. Step 2: The sign tells you to take away positive 1. Step 3: You don’t have positive 1 to take away, so you must add one zero pair. Step 4: Take away positive 1. Step 5: Look at the set and record your answer.

11. Another Look at Example 2: -2 - 1 = -3 When using markers to model, be careful to write only the amount you see. A model of the -2 - 1 can also look like this:

12. Example 3: -2 - (-3) = 1 When using markers to model, use zero pairs to add maekers to your mat when needed. Step 1: Model the first number. Step 2: The sign tells you to take away negative 3. Step 3: You don’t have negative 3 to take away, so you must add one zero pair. Step 4: Take away negative 3 and you have your answer.

13. Closure Step 1: Model the first number. Step 2: The sign tells you what to do. Step 3: If you don’t have enough counters to perform the operation, add zero pairs. Step 4: Review you set and record your answer.

14. Practice Time! Take out your workspace! When using markers to model, be careful to write only the amount you see.