Unit Plan 3 (Grade 2 Math): One- and Two-Step Word Problems within 100
Model and solve addition and subtraction word problems within 100—unknowns in all positions—using drawings, tape diagrams, and equations; students explain reasoning, choose operations that fit the story, and check answers for sense and accuracy.
Focus: Model and solve addition/subtraction problems with unknowns in all positions; use drawings/equations and explain reasoning.
Grade Level: 2
Subject Area: Mathematics (Problem Solving • Modeling)
Total Unit Duration: 5 sessions (one week), 35–45 minutes per session
I. Introduction
This week builds flexible problem solvers who can make sense of situations, choose representations (drawings, bar/tape diagrams, number lines), and write equations with an unknown to match. Students tackle one- and two-step problems within 100 and justify their choices and checks.
Essential Questions
- How do I decide what the problem is asking and which operation fits?
- How can a model (picture, tape diagram, number line) help me keep track of parts and the unknown?
- How do I check if my answer makes sense in the story?
II. Objectives and Standards
Learning Objectives — Students will be able to:
- Identify the unknown position (result unknown, change unknown, start unknown) and select a model/operation that fits.
- Represent problems with drawings (cubes, quick pictures), bar/tape diagrams, or number lines and write equations using a symbol for the unknown.
- Solve one- and two-step problems within 100 and explain why the method works.
- Use estimation and story sense to check reasonableness; revise as needed.
- Communicate thinking with mathematical language and labeled representations.
Standards Alignment — CCSS Grade 2 (spiral across the unit)
- 2.OA.1: Use addition and subtraction within 100 to solve one- and two-step word problems with unknowns in all positions, using drawings and equations with a symbol for the unknown.
- Mathematical Practices: MP.1 (Make sense of problems & persevere) and MP.4 (Model with mathematics) emphasized; MP.3, MP.5, MP.6 present through explanation, tool use, and precision.
Success Criteria — Student Language
- I can find the unknown, choose a model, and write an equation that matches the story.
- I can solve and then check if my answer makes sense in the story.
- I can explain my steps using math words and labeled drawings.