**Click here for the Spanish version: https://youtu.be/HuhZwdTQh9E**

**In This Unit of Study…**

Students apply and communicate their knowledge of problem types, such as adding to, taking from, putting together, and comparing (within 100). Students will represent their mathematical thinking as they solve one- and two-step problems through a progression of concrete, pictorial, and abstract representations. Students will add and subtract (within 1,000) by using concrete models such as base ten blocks and linking cubes. They will also use pictorial models that include drawings and the use of number lines and the bar model. Students will extend their understanding of addition and subtraction, using strategies based on place value, properties of operation, and the relationship between addition and subtraction. Composing and decomposing a ten will be referenced so students can use strategies that involve making a 10, making a 100, and breaking apart a 10. Students will also determine the unknown whole number in an addition or subtraction equation with the unknown in any position.

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

- MA.2.NSO.2.4 Explore the addition of two whole numbers with sums up to 1,000. Explore the subtraction of a whole number from a whole number, each no larger than 1,000.
- MA.2.AR.1.1 Solve one- and two-step addition and subtraction real-world problems.
- MA.2.AR.2.2 Determine the unknown whole number in an addition or subtraction equation, relating three or four whole numbers, with the unknown in any position.

**Key Concepts:**

- I can solve one- and two-step real-world addition and subtraction problems within 100.
- I can determine the unknown whole number in an addition equation, relating three or four whole numbers, with the unknown in any position.
- I can determine the unknown whole number in a subtraction equation, relating three or four whole numbers, with the unknown in any position.
- I can add within 1,000 using manipulatives, number lines, drawings, or properties of operations or place value.
- I can subtract within 1,000 using manipulatives, number lines, drawings, or properties of operations or place value.
- I can understand that it is necessary to compose and decompose ones, tens, and hundreds when needed to add or subtract with 1,000.