📐 Standards Alignment

2.NBT.B.5 CCSS.MATH

Fluently add and subtract within 100 using strategies based on place value and properties of operations.

2.NBT.B.9 CCSS.MATH

Explain why addition and subtraction strategies work using place value and operation properties.

View all Grade 2 Mathematics standards →

📦 Materials Needed

Base-ten blocks
Place-value chart
Dry-erase board
Two-digit number cards

🎯 Teaching Strategies

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Model the Trade with Base-Ten Blocks Have students physically trade 10 ones for 1 ten and 1 ten for 10 ones before using the written method.

💡

Connect Expanded Form to the Algorithm Write numbers in tens-and-ones form so students can explain why regrouping works.

💡

Mix Equations and Story Problems Students understand regrouping better when they choose the operation from context instead of only solving columns of numbers.

⚠️ Common Misconceptions

❌ Misconception

Students add the ones but forget the regrouped ten

✅ Correction

Circle the regrouped ten and point to it again when adding the tens column.

❌ Misconception

Students think subtracting always means the bigger digit goes on top in each column

✅ Correction

Return to place-value blocks and show why a ten must sometimes be broken apart first.

📊 Differentiation Tips

Struggling

Stay with two-digit numbers under 50 and use base-ten blocks for every problem.

On-level

Move between blocks, drawings, expanded form, and the standard algorithm.

Advanced

Ask students to explain regrouping in words and compare two solution strategies.

🚀 Extension Activities

Play a regrouping card game with two-digit numbers.
Write matching addition and subtraction fact-family stories.
Solve shopping stories that require regrouping with prices under one dollar.