Year Long: Addition and Subtraction Facts to 20 Mastered (Facts Known Within 3 to 5 seconds)
Specific Strategies: Addition Facts
Number + 1 (counting on) When you add 1 to a number, you get the next number.
Number + 2 (counting on) When you add 2 to a number, you skip the next number and go to the next. At Home Connection: Draw a card and then snap finger twice for the number (counting up with each snap)
Number + 3 (counting on) When you add 3 to a number, you put the number in your head and then count up 3. At Home Connection: Draw a card and then snap finger three times for the number (counting up with each snap)
Adding 10 17 means 1 ten and 7 ones or 10+7
9 + a number After you know 10 + a number, think of the 9 as 10, then subtract 1. (9+4….think 10+4=14 then -1 = 13)
Combinations of 10 After seeing the pattern, you must memorize the combinations that make 10 (9+1, 8+2, 7+3, 6+4, 5+5) Play go fish. Instead of asking for a matching number ask for the card that make the combination of ten. Deal out 7 cards and pull out the combinations of 10. Draw a new card and see if you have the combination in your hand. Play memory and match the combinations of 10.
Doubles These are 2 of the same number. The sums are always even and need to be memorized. Draw a card and double the number
Doubles +1 These are numbers that are together in counting order, ex. 4+5, 7+8. Double the smaller number and add 1 (4+5 is 4+4=8 then +1 = 9) Draw a card and double the number, then add 1
2 Apart These are numbers that skip a number when counting such as 5+7, 6+8. Think of the number in the middle and double it. (5+7 is 6+6=12)
The Remaining Facts Use what you know to figure these out. 7+4 (7+3=10 then +1 =11) 8+4 (8+2=10 then +2 =12) 8+5 (8+2=10 then +3 =13)
Specific Strategies: Subtraction Facts
Number-Number When you subtract a number from the same number, the answer is always 0. Draw a card. Subtract the same number from the card you drew. (draw a 6, think, 6-6=0)
Numbers Next Door When you subtract numbers next to each other on the number line, the answer is always 1.
Number -1, -2, -3 Put the number in your head and count backward.
Count up if it’s close If the numbers are close to each other on the number line, start at the smaller one and count up to the larger and see how many it takes.
10 – Number Memorizing the combinations of 10 for the addition strategies makes this easy to reverse.
Doubles Memorizing the sums of the doubles like 6+6 or 8+8 should make 12-6 and 16-8 easy to reverse.
Teen number -10 and Teen number - number Knowing 10+a number from the addition strategies makes facts like 17-10=7 and 17-7=10 easy to figure out.
Stop at 10 when counting up ex. 16-7 (7 to 10 is 3, 10 to 16 is 6 so 3+6=9)
Additional Skills Related to Addition and Subtraction
Students demonstrate they have the ability to: * Use addition and subtraction within 20 to solve one- and two-step word problems. Example One Step: Bob had 14 apples. He sold 9. How many apples does he have now? OR Bob had some apples. He sold 9. Now he has 5. How many apples did Bob have to start? Example Two Step: Sarah had 5 red pencils and 6 blue pencils. She bought 8 more at the store. How many pencils does Sarah have now? OR Sarah had $15. She spent $7 on a new book. The next day her mom gave her $10. How much money does she have now?
* Explain why addition and subtraction strategies work, using place value and the properties of operations. Beginning of Year Example: 9 + 7=I can take one from the 7 to make 9 into 10, then 10 plus 6 is 16. Mid Year Example 2: Click Here End of Year Example 3: Click Here
* Solve word problems involving addition and subtraction within 20, by using objects, drawings, and equations to represent the problem.
* Relate counting to addition and subtraction. Example (Fact Families): 9 + 7 = 16, 7 + 9 = 16, 16 - 7 = 9, 16 - 9 = 7
*Students will recognize or recall specific vocabulary, such as: Add, addend, addition, difference, mental, model, number, number line, operation, property, relationship, represent, strategy, subtract, subtraction, sum, word problem, equation