Do Now Solve the problems in the most efficient way you can = ____10 – 7 = ____ = ____18 – 9 = ____ = ____84 – 40 = ____

Addition and Subtraction Strategies in First Grade How to Become a More Efficient Mathematician

1 st Grade Expectations Master a number of different addition/subtraction strategies. Choose the strategies that work best for him/her and for the particular problem. Be flexible with strategies and choose ones that are efficient. Check work with another strategy.

Full Model Prompt: How can you use a picture to solve this problem? Drawing all for addition Counting objects, counting on fingers, drawing a picture Crossing off for subtraction Taking away objects, taking away fingers, crossing off in a picture

Counting On/Counting Back Prompt: How can you use a number line and/or counting to solve this problem? Adding and subtracting are like counting up and back Start with the larger number and count on or back (“hop”/”jump” forward or back) Efficient strategy for solving single-digit addition and subtraction problems Show your work with a number line or drawing Examples: = ___8 – 2 = ___

Using Facts We Know (Fluency) Prompt: How can you use facts you know to solve this problem? Combinations of = ____I know = 10 and = 13 Doubles and Near Doubles = _____I know = 14, so one more is 15 Fact Families – using what we know about addition to help with subtraction 10 – 7 = ____I know = 10, so 10 – 7 = 3

Keep One/Break One Prompt: How can you break a number into helpful parts to solve this problem? Break one number into two parts so that you can make a landmark number (e.g., 10 or a multiple of 10) = ____ 18 – 9 = ____ = ____

Using Place Value Prompt: How can you use what you know about 10s and 1s to solve this problem? = ____ Base 10 Model: Using or drawing base 10 blocks Expanded Form: Breaking numbers into 10s &1s = 58 Keep One/Break One: Adding multiples of 10 first = = 58