Primary Standards:
MAFS.3.NBT.1.2: Fluently add and subtract within 1,000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.
MAFS.3.OA.4.8: Solve two-step word problems using the four (addition or subtraction) operations. Represent these problems using equations with a letter (symbol) standing for the unknown quantity. Assess the reasonableness of answers using mental computation and estimation strategies including rounding.
Content Knowledge:
In 2nd grade, students built conceptual understanding and procedural skills using adding and subtracting within 100. They used concrete models and the number line to explore addition and subtraction 1,000. The goals of the standard extend previous experiences to becoming fluent, which include being accurate and efficient. In 3rd grade, students continue adding and subtracting within 1,000, extending their understanding of place value by composing and decomposing tens and hundreds. They develop and apply strategies based on place value, properties of operations, and the relationship between addition and subtraction.
When working with various strategies, it is important to note that there is no right or wrong strategy. Students should be allowed to choose the strategy that works best for them. Students should also not be expected to master all strategies or be forced into a strategy that they do not understand. As students focus on accuracy and continue to develop efficiency over time, it is important students share their strategies so that they realize that there are many ways to achieve the correct answer.
GCG 1 Learning Goal: As a mathematician,I will be able to use strategies to fluently multiply by 4
- Step 1: Connect x2 facts (doubles) to x4 facts (double-doubles)
- Step 2: Decide when to apply the Commutative property and use other known facts for efficiency
GCG 2 Learning Goal: As a mathematician,I will be able to use a variety of models, representations, and strategies to add within 1,000
- Step 1: Use base ten models (concrete and pictorial) to develop place value understanding and add within 1,000
- Step 2: Use expanded form/partial sums and place value understanding to add within 1,000
- Step 3: Use place value understanding and open number lines to decompose addends and count up to add within 1,000
GCG 3 Learning Goal: As a mathematician,I will be able to use a variety of models, representations, and strategies to subtract within 1,000
- Step 1: Use base ten models (concrete and pictorial) to develop place value understanding and subtract within 1,000
- Step 2: Use expanded form/partial differences and place value understanding to subtract within 1,000
- Step 3: Use place value understanding and open number lines: to subtract partial differences and add up to subtract within 1,000
