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 TilesTo 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)
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)