Adding signed numers using algebra tiles

1. AIM: What are the patterns for adding signed numbers ? OBJECTIVE: S.W.B.A.T. use manipulative to add signed integers and develop a pattern for general addition of signed numbers. Homework: Practice with Adding Signed Integers worksheet September 18, 2007 DO NOW Get a worksheet and finish example 1

2. Adding Signed Numbers – debrief of do now Example 1 3 3 3 3 3 3 3 3 3 3 + 3 +2 +1 +0 +-1 +-2 +-3 +-4 +-5 +-6 6 5 4 3 2 1 0 -1 -2 -3

3. Adding Signed Numbers – Example 2 5 5 5 5 5 5 5 5 5 5 + 0 +-1 +-2 +-3 +-4 +-5 +-6 +-7 +-8 +-9 5 4 3 2 1 0 -1 -2 -3 -4

4. Adding Signed Numbers – Opposites Opposites are numbers which have the same size but different signs. On the number line they are the same distance from zero. -4 and 4 are opposites -1 and 1 are opposites When you add two opposites you always get zero!

5. Adding Signed Numbers – Using Reds and Yellows How can we use reds and yellows to add -8 + 7 ? -8 7 - 7 + 7 = 0 1 red = -1

6. Adding Signed Numbers – Using Reds and Yellows How can we use reds and yellows to add -10 + 5 ? -10 5 - 5 + 5 = 0 5 reds = -5

7. Adding Signed Numbers – Using Reds and Yellows How can we use reds and yellows to add -9 + -3 ? -9 -3 12 reds = -12 When adding 2 negative numbers you will always get a negative number!

8. Adding Signed Numbers – Using Reds and Yellows How can we use reds and yellows to add -2 + 4 ? -2 4 - 2+ 2 = 0 2 yellows = 2

9. Adding Signed Numbers – What is the “rule” ? When adding numbers of mixed sign the answer will have the same sign as the “bigger number.” The size of the answer will be the smaller number subtracted from the biggest number. Example: -6 + 3 What will the sign of the answer be? What will the size of the answer be ? Negative because -6 is the “bigger” number 6 – 3 = 3 -3

10. Adding Signed Numbers – Groupwork Worksheet: 3,4,6