3. Palmdale School District Mathematics Content Standards Grade 2 NUMBER SENSE Students: 2.1 understand and use the inverse relationship between addition and subtraction (e.g., an opposite number sentence for 8 + 6 = 14 is 14 - 6 = 8) to solve problems and check solutions.

4. Understanding the Fact Family relationship.

5. SUBTRACTIONADDITION Fact Family 6, 8, & 14 6 + 8 = 14 8 + 6 = 14 14 - 6 = 8 14 - 8 = 6

6. We are starting with A Total of Fourteen Apples

7. 68 = 14 ADDITION

8. 86= 14 ADDITION

9. SUBTRACTION 146 = 8

10. SUBTRACTION 148= 6

11. Understanding how to check your answers using Fact Families.

12. Defining Terms Sum Parts of an addition Problem 6 + 8 = 14 Addend

13. We know that: 6 + 8 = 14 How To Check ADDITION PROBLEMS With Subtraction Check answer by subtracting an addend from the sum: 14 - 6 YOUR ANSWER SHOULD BE THE SECOND ADDEND!!!! = 8

14. We know that: 8 + 6 = 14 How To Check ADDITION PROBLEMS With Subtraction Check answer by subtracting an addend from the sum: 14 - 8 YOUR ANSWER SHOULD BE THE SECOND ADDEND!!!! = 6

15. Defining Terms Difference Parts of a subtraction Problem 14 - 6 = 8 Starting Number Take Away Number

16. We know that: 14 - 6 = 8 How To Check SUBTRACTION PROBLEMS With Addition Check answer by adding the answer to the take away number: 8 + 6 YOUR ANSWER SHOULD BE THE STRATING NUMBER!!!! = 14

17. We know that: 14 - 8 = 6 How To Check SUBTRACTION PROBLEMS With Addition Check answer by adding the answer to the take away number: 6 + 8 YOUR ANSWER SHOULD BE THE STRATING NUMBER!!!! = 14

18. Practice Problems

19. EXAMPLE Directions:Make fact families out of the given numbers. Example: 2, 3, 5 3 + 2 = 5 2 + 3 = 55 - 2 = 3 5 - 3 = 2

20. GUIDED PRACTICE Part One Directions: Make fact families out of the given numbers. 1) 4, 5, 92) 2, 5, 7 3) 4, 7, 114) 8, 9, 17 Reminder: four problems make up a fact family: two addition and two subtraction.

21. GUIDED PRACTICE ANSWERS 1) 4, 5, 9 4 + 7 = 11 11 - 4 = 7 7 + 4 = 11 11 - 7 = 4 2) 2, 5, 7 2 + 5 = 7 7 - 2 = 5 5 + 2 = 7 7 - 5 = 2 3) 4, 7, 11 4 + 7 = 11 11 - 4 = 7 7 + 4 = 11 11 - 7 = 4 4) 8, 9, 17 8 + 9 = 17 17 - 8 = 9 9 + 8 = 17 17 - 9 = 8

22. EXAMPLE Directions: Solve the given problem, then check your answer using fact families. Example: 5 + 4 5 + 4 = 99 - 5 = 4 Problem: Check: Is the answer correct? Yes, because the check answer is the same as the other addend.

23. 10 - 6 = 46 + 4 = 10 EXAMPLE Directions: Solve the given problem, then check your answer using fact families. Example: 10 - 6 Problem: Check: Is the answer correct? Yes, because the check answer is the same as the starting number.

24. GUIDED PRACTICE Part Two Directions: Solve the given problem, then check your answer using fact families. 1) 7 + 6 =2) 12 - 5 = 3) 9 + 4 =4) 16 - 9 =

25. GUIDED PRACTICE ANSWERS 1) 7 + 6 = PROBLEM: 7 + 6 = 13 2) 12 - 5 = PROBLEM: 12 - 5 = 7 3) 9 + 4 = PROBLEM: 9 + 4 = 13 4) 16 - 9 = PROBLEM: 16 - 9 = 7 CHECK: 13 - 6 = 7 CHECK: 7 - 5 = 12 CHECK: 13 - 9 = 4 CHECK: 7 + 9 = 16