Standard

Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.

Student language:

• "I can add and subtract with regrouping."

Explanation

About the Math, Learning Targets, and Rigor

This standard builds on their knowledge by increasing the size of numbers (two 3-digit numbers). Strategies are similar to those stated in 2.NBT.5, as students extend their learning to include greater place values moving from tens to hundreds to thousands.

Students use number lines, base ten blocks, pictorial representations, etc. to show, solve and explain reasoning. Explanation of thinking is a critical component of this standard.

See Addition and Subtraction strategy sheets.

Common Misconceptions

• Students may think that the 4 in 46 represents 4, not 40 or 4 tens. Students need many experiences representing two and three-digit numbers with manipulatives that group (base ten blocks) and those that do NOT group, such as counters, etc.
• When adding two-digit numbers, some students might start with the digits in the ones place and record the entire sum. Then they add the digits in the tens place and record this sum. Assess students’ understanding of a ten and provide more experiences with manipulatives like base-ten blocks.
• When subtracting two-digit numbers, students might start with the digits in the ones place and subtract the smaller digit from the greater digit. Then they move to the tens and the hundreds places and subtract the smaller digits from the greater digits. Assess students’ understanding of a ten and provide more experiences with manipulatives like base-ten blocks.

Resources

Videos

• Instructional Video (6:18 - 12:29)
• Khan Academy
  • scroll to find 2.NBT.7, click on a skill, watch videos on left side in each skill
• Learn Zillion

EngageNY Lessons

Extra Practice

• North Carolina Tasks
• Illustrative Math Tasks
• Howard County Tasks
  • Click on 2nd grade at bottom, then 2.NBT.7
• Common Core Sheets

Released Assessment Questions

2.NBT.7 Student Example

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