Unit Plan 4 (Grade 5 Math): Decimal Operations—Add & Subtract in Context
5th graders add and subtract decimals to hundredths using models, estimation, and real-world problems. Students connect visual strategies to standard algorithms, align decimals precisely, check with inverses, and explain reasoning for accuracy and reasonableness.
Focus: Add and subtract decimals to hundredths using estimation, place-value models, and word problems; connect strategies to a written method and explain reasoning.
Grade Level: 5
Subject Area: Mathematics (Number & Operations in Base Ten — Decimal Operations)
Total Unit Duration: 5 sessions (one week), 45–60 minutes per session
I. Introduction
Students develop conceptual and procedural fluency for adding and subtracting decimals to hundredths. They use grids, base-ten models, money, and number lines to make sense of operations, then connect models to aligned algorithms and estimation for reasonableness. Context-rich problems highlight units, precision, and the relationship between addition and subtraction.
Essential Questions
- How do place-value models help me understand decimal addition and subtraction?
- Why must decimal places be aligned, and how do I regroup correctly?
- When should I use an estimate versus an exact calculation?
- How do I explain my method and check my result for reasonableness?
II. Objectives and Standards
Learning Objectives — Students will be able to:
- Add and subtract decimals to hundredths using models (grids, number lines, money) and place-value reasoning.
- Align decimals and apply the standard algorithm with correct regrouping and trailing zeros as needed.
- Use estimation strategies (rounding, front-end estimation, compatible numbers) to predict and check answers.
- Explain how addition and subtraction are related and use inverses to self-check.
- Solve multi-step word problems, choosing appropriate precision and units, and communicate reasoning clearly.
Standards Alignment — CCSS Grade 5
- 5.NBT.7: Add, subtract, multiply, and divide decimals to hundredths 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 and explain the reasoning used.
- Mathematical Practices emphasized: MP.1 (make sense), MP.3 (justify/critique), MP.4 (model), MP.6 (precision), MP.7 (structure), MP.8 (regularity).
Success Criteria — Student Language
- I can add and subtract decimals to hundredths and show how I know using a model.
- I can line up decimal places, use trailing zeros if needed, and regroup correctly.
- I can estimate first, then compare my estimate and exact answer.
- I can use inverse operations to check my work.
- I can explain my steps and label my units clearly.