1. Write and Evaluate Expressions GOAL: By the end of this lesson, we will ALL be able to write and evaluate addition and subtraction expressions

2. Review Identity Property: Associative Property: Commutative Property: 0 Ex: 5 + 0 = 5 ( ) Ex: (1+2) + 3 = 1 + (2+3) Flip-Flop; any order Ex: 5+4 = 4+5

3. Name this property … 46 + 21 = 21 + 46 Commutative Property

4. Name this property … 69 + 0 = 69 Identity Property

5. Name this property … 35 + (42 +56) = (35 + 42) + 56 Associative Property

6. Name this property … 93 + 28 = 28 + 93 Commutative Property

7. Name this property … 16 + (24 + 18) = (16 + 24) + 18 Associative Property

8. Name this property … 99 + 0 = 99 Identity Property

9. GOAL: By the end of this lesson, we will ALL be able to write and evaluate addition and subtraction expressions Expression – has numbers and operation signs but does not have an equal sign Example: (15 + 5) – 7 Variable – a letter or symbol that represents an unknown number Example: 18 – n

10. # 1 Rule!!!!!!!! Remember to ALWAYS do parentheses first!

11. Find the value of each expression … Remember to ALWAYS do parentheses first! 14 + (7 +3) 14 + (10) 14 + 10 = 24

12. Find the value of each expression … Remember to ALWAYS do parentheses first! 17 – (6-5) 17 – (1) 17 - 1 = 16

13. Find the value of each expression … Remember to ALWAYS do parentheses first! (9-8) + 4 (1) + 4 1 + 4 = 5

14. Find the value of each expression … Remember to ALWAYS do parentheses first! (6 + 9) - 2 (15) - 2 15 - 2 = 13

15. Find the value of each expression … Remember to ALWAYS do parentheses first! __ - 18 if __ = 30 ___ = 30 30 – 18 = 12

16. Find the value of each expression … Remember to ALWAYS do parentheses first! 8 - __ if __ = 6 __ = 6 8 – 6 = 2

17. Find the value of each expression … Remember to ALWAYS do parentheses first! 20 – (5 – c) if c = 3 C = 3 20 – (5-3) 20 – (2) 20 – 2 = 18

18. Write an expression to match the words … Remember you might need to add parentheses! Tom caught 15 fish. He caught 7 more. He threw 2 back. (15 + 7) - 2

19. Which number makes the equation __ + 5 = 14 true? A.8 B.9 C.10 B. 9

20. Did we meet our goal today? GOAL: By the end of this lesson, we will ALL be able to write and evaluate addition and subtraction expressions Any questions?