Unit Plan 18 (Grade 4 Math): Mixed Operations—Reasonableness & Representation
Solve multi-step problems using all four operations; model with diagrams and equations; estimate and check answers for reasonableness while interpreting units and remainders in context.
Focus: Tackle multi-step problems mixing the four operations; estimate, compute, and check.
Grade Level: 4
Subject Area: Mathematics (Operations & Algebraic Thinking; Number & Operations in Base Ten; Measurement & Data)
Total Unit Duration: 5 sessions (one week), 45–60 minutes per session
I. Introduction
Students plan and solve multi-step problems that blend addition, subtraction, multiplication, and division. They use representations (tape/strip diagrams, bar models, number lines, tables, equations) to make sense of contexts, and they practice reasonableness checks with estimation, units, and inverse operations.
Essential Questions
- How do I choose the operation(s) and representation that fit a situation?
- Where and how should I estimate to check if my answer is reasonable?
- How do units and context guide decisions (e.g., rounding, remainders, interpretation)?
II. Objectives and Standards
Learning Objectives — Students will be able to:
- Decompose multi-step word problems and select operations that match each step.
- Model situations with tape/strip diagrams, bar models, number lines, tables, and equations.
- Use estimation (rounding, compatible numbers, benchmarks) before and after computing to check reasonableness.
- Track units (time, volume, mass, money) and interpret results (including remainders) in context.
- Communicate solutions with labeled representations, clear equations, and a written justification.
Standards Alignment — CCSS Grade 4
- 4.OA.3: Solve multistep word problems posed with whole numbers using the four operations; represent with equations using a letter for the unknown; assess reasonableness of answers using mental computation and estimation strategies including rounding.
- Connection: 4.MD.2 (solve word problems involving intervals of time, liquid volumes, and masses of objects, using the four operations; represent quantities and use diagrams as needed).
Success Criteria — Student Language
- I can choose operations and a model that match the problem and explain why.
- I can estimate before and check after to show my answer makes sense.
- I can keep units accurate and justify decisions (like rounding or remainders) using the context.