Wyoming Math 2.NBT.7a
The Standard
Add and subtract within 1,000, using concrete models or drawings and strategies based on place value, properties of addition, and/or the relationship between addition and subtraction: Relate the strategy to a written method and explain the reasoning used.
2023 Wyoming Mathematics Content and Performance Standards · Use place value understanding and properties of operations to add and subtract.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students add and subtract numbers up to 1,000 with blocks or place-value sketches. They match each trade in their model to a written calculation and explain why it works.
What Mastery Looks Like
- A student models 326 + 187 and gets 513, showing the trades in their written work. They solve 402 − 178 as 224 by trading across the empty tens place. They check by adding 224 + 178.
Common Misconceptions
- Students may forget to include a traded ten when adding the tens column. When subtracting 178 from 402, they may write 7 for the tens because they do not know how to trade through a zero.
How to Assess It
- Exit ticket: Solve 402 − 178 with a place-value drawing and a written method. Write one sentence explaining the two trades.
Lesson moves
Ways to Teach It
Give pairs base-ten blocks to model 326 + 187, make the trades, and record each one beside a written calculation.
Ask, "Why can you trade one hundred for ten tens in 402 − 178?" Have students explain with a place-value sketch.
Partners draw two number cards from 100 to 450, add or subtract the smaller from the larger, then compare sketches with written work.
Show a library slip with 402 books and 178 checked out, then have students sketch and calculate how many remain.
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Printable 2.NBT.7a Worksheet
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