Primary Standards:
MAFS.2.OA.2.2 Fluently add and subtract within 20 using mental strategies. By end of Grade 2, know from memory all sums of two one-digit numbers.
Connecting Standards:
MAFS.2.NBT.2.9 Explain why addition and subtraction strategies work, using place value and the properties of operations.
Content Knowledge:
It is not expected students will attain fluency with facts from this Unit within the time-frame of a single Unit. Fluency should be focused on and assessed throughout the year using Number Talks, games, centers, etc. It is the goal of the standard that students attain fluency with addition and subtraction facts within totals of 20 by the end of the year.
The study of math facts in second grade is about understanding operations, equations, and properties. It is about using known facts, like doubles and making tens, to make sense of and determine the sums and differences for related, but more complex facts. Second grade is also about gaining strong number understandings and fluency with math facts that allow our students to tackle the more complex computations they will perform later in the year as well as in third grade and beyond. Students have worked on strategies in prior grades including Counting On/Back (0, 1, and 2) Doubles, Near Doubles, Combinations of Ten, Adding Ten, Subtracting Ten, Making a Ten, and Using Related Facts. Students do not have to be fluent with all mental strategies. They should have many opportunities to practice, explain, and compare strategies. Students will apply strategies in practice opportunities which will lead to them becoming fluent with facts.
GCG 1 – Learning Goal: As a mathematician, I can Identify and solve addition facts using the “Make a Ten and Some More” strategy MAFS.2.OA.2.2
- Step 1: Use manipulatives to visualize the way numbers are broken apart and put back together to “make ten and some more”
- Step 2: Use an open number line to solve “make a ten and some more” facts
- Step 3: Identify and solve facts for the “make a ten and some more” strategy
GCG 2 – Learning Goal: As a mathematician, I can Identify and solve subtraction facts using the “Make a Ten” strategy MAFS.2.OA.2.2
- Step 1: Find differences using “Make a Ten” by counting up using the related unknown addition fact
- Step 2: Find differences by subtracting to get to ten and then subtracting the rest
- Step 3: Explain how to find a difference using the make a ten strategy
GCG 3 – Learning Goal: As a mathematician, I can Identify and solve doubles and near doubles facts MAFS.2.OA.2.2