Addition and subtraction 2

Students use the making-ten strategy to add within 20. They decompose one addend to make a ten with the other, then add the remaining ones.

2.OA.B.2: Flexibly and efficiently add and subtract within 20 using multiple mental strategies which may include counting on; maki...

Students subtract within 20 by decomposing numbers. They break apart the subtrahend to first get to ten, then subtract the rest.

2.OA.B.2: Flexibly and efficiently add and subtract within 20 using multiple mental strategies which may include counting on; maki...

Students use doubles facts and near-doubles strategies to add and subtract within 20. They build fluency by recognizing relationships between known and unknown facts.

2.OA.B.2: Flexibly and efficiently add and subtract within 20 using multiple mental strategies which may include counting on; maki...

Students demonstrate fluency adding and subtracting within 20 using mental strategies. They select the most efficient strategy for each problem.

2.OA.B.2: Flexibly and efficiently add and subtract within 20 using multiple mental strategies which may include counting on; maki...

Students explain why addition strategies work using place value and properties of operations. They use words, pictures, and equations to justify their methods.

2.NBT.B.9: Explain why addition and subtraction strategies work, using place value and the properties of operations. These explanat...

Students explain why subtraction strategies work by connecting to place value and the relationship between addition and subtraction. They justify each step of their method.

2.NBT.B.9: Explain why addition and subtraction strategies work, using place value and the properties of operations. These explanat...

Students use the relationship between addition and subtraction to verify their answers. They explain how knowing one operation helps solve the other.

2.NBT.B.9: Explain why addition and subtraction strategies work, using place value and the properties of operations. These explanat...

Students analyze different addition and subtraction strategies presented by others. They explain errors, suggest corrections, and justify which strategies are most efficient.

2.NBT.B.9: Explain why addition and subtraction strategies work, using place value and the properties of operations. These explanat...

Students determine whether a number is even or odd by pairing objects. They discover that even numbers can be split into two equal groups with none left over.

2.OA.C.3: Determine whether a group of objects (up to 20) has an odd or even number of members, e.g., by pairing objects or counti...

Students identify whether numbers up to 20 are even or odd. They use pairing, arrays of two rows, and the pattern of ones digits to classify numbers.

2.OA.C.3: Determine whether a group of objects (up to 20) has an odd or even number of members, e.g., by pairing objects or counti...

Students write equations to express even numbers as the sum of two equal addends. They connect the definition of even numbers to repeated addition.

2.OA.C.3: Determine whether a group of objects (up to 20) has an odd or even number of members, e.g., by pairing objects or counti...

Students solve problems involving even and odd numbers up to 20. They predict whether sums of even and odd numbers will be even or odd and explain their reasoning.

2.OA.C.3: Determine whether a group of objects (up to 20) has an odd or even number of members, e.g., by pairing objects or counti...