1. Using Models to Add Integers
Quick Review

2. Modeling Integers with Number Lines
An integer can be modelled by an arrow on a number line. To add integers using a number line, place the arrows representing the integers head-to-tail. Example 1: Add: (–6) + (+4)

3. Modeling Integers with Tiles
An integer can also be modelled using coloured tiles.
One blue tile models –1.
One red tile models +1.

4. Modeling Integers with Tiles
+1 and –1 are opposite integers.
Opposite integers have the same size and opposite signs.
They combine to form a zero pair.
(+1) + (–1) =

5. How To Add with Tiles
To add integers using coloured tiles, we combine the tiles that represent the integers. Then, we remove any zero pairs and count the remaining tiles. Add: (+5) + (–3)

6. How to Add with Tiles

7. Using a Number Line to Subtract Integers
To subtract integers using a number line, add the opposite integer. On a number line, the arrows representing opposite integers have the same length, but point in opposite directions. +3 and –3 are opposite integers

8. How to Subtract with Number Lines
Example: Subtract: (+2) – (+7)

9. How to Subtract with Tiles
Model the first integer with tiles, then remove the tiles that represent the second integer. When you do not have enough tiles to remove, add zero pairs. Example: Subtract: (–3) – (–8)

10. How to Subtract with Tiles
Model –3 with 3 blue tiles: To take away –8, we need 5 more red tiles. Add 5 zero pairs.

11. How to Subtract with Tiles
Take away 8 blue tiles. 5 red tiles remain. They represent +5. (–3) – (–8) = +5

12. Check Your Understanding
Using Number Lines or Tiles, complete the Check questions #1-5 on the Activating Prior Knowledge handout. #1-3 (Adding Integers) #4-5 (Subtracting Integers)