**Click here for the Spanish Version: https://youtu.be/HVIbfTbfpEc**

**In This Unit of Study…**

Students use and explain a variety of counting strategies, and they reason about the sums and difference of basic facts through sums of 10. After using one-to-one correspondence to count a set of items, students begin to find more efficient methods for counting. Students relate the concept of counting on to addition and counting back to subtraction. The ability to add and subtract within 10 translates to being able to find the sum of 3 whole numbers. Students represent such problems by using objects, drawings, and equations with a symbol for the unknown, while understanding that the sum or difference can be on either side of the equal sign.

**B.E.S.T. Benchmarks**

- MA.1.NSO.2.2 Add two whole numbers with sums from 0 to 20 and subtract using related facts with procedural reliability. (only within 10)
- MA.1.AR.1.1 Apply properties of addition to find a sum of three or more whole numbers. (only within 10)
- MA.1.AR.1.2 Solve addition and subtraction real-world problems using objects, drawings, or equations to represent the problem.
- MA.1.AR.2.1 Restate a subtraction problem as a missing addend problem using the relationship between addition and subtraction.
- MA.1.AR.2.3 Determine the unknown whole number in an addition or subtraction equation, relating three whole numbers, with the unknown in any position.

**Key Concepts**

- I can solve real-world addition and subtraction problems within 10 using objects to represent the problem.
- I can solve real-world addition and subtraction problems within 10 using drawings to represent the problem.
- I can solve real-world addition and subtraction problems within 10 using equations to represent the problem.
- I can apply properties of addition by grouping numbers together to find the sum of the three or more whole numbers.
- I can add two whole numbers with sums to 10 and subtract using a reliable method such as adding to, putting together, comparing, and taking from.
- I can use the relationship between addition and subtraction to restate a subtraction problem as a missing addend problem.