Unit Plan 20 (Grade 1 Math): Tens & Ones Games—Fluency Power-Up

Focus: Build automaticity adding/subtracting multiples of ten using place-value reasoning, open number lines, and hundreds charts; notice and use patterns.

Grade Level: 1

Subject Area: Mathematics (Number & Operations in Base Ten)

Total Unit Duration: 5 sessions (one week), 45–60 minutes per session

I. Introduction

Students strengthen mental computation by making +10/−10 moves and subtracting multiples of ten from two-digit numbers. Through fast-paced games, they use tens and ones structure, open number lines, and hundreds charts to reason and explain shortcuts, emphasizing regularity in repeated reasoning.

Essential Questions

• How do tens and ones help me add or subtract multiples of ten quickly?
• When is an open number line or hundreds chart the best tool?
• What patterns do I notice when I keep adding or subtracting 10?

II. Objectives and Standards

Learning Objectives — Students will be able to:

1. Find 10 more/10 less than a two-digit number mentally and explain using place value.
2. Add/subtract multiples of ten (e.g., ±20, ±30, ±40) to/from two-digit numbers using open number lines or hundreds charts.
3. Describe and use patterns (same ones, tens change) to compute efficiently.
4. Choose and justify a representation (chart, line, blocks) and check reasonableness.
5. Generalize if… then… statements about repeated +10/−10 moves (MP.8).

Standards Alignment — CCSS Grade 1 (threaded across the unit)

• 1.NBT.5: Given a two-digit number, mentally find 10 more or 10 less without counting; explain the reasoning.
• 1.NBT.6: Subtract multiples of ten (10–90) from multiples of ten within 100 using concrete models/strategies; relate to a written method.
• Mathematical Practices: MP.8 emphasized (look for and express regularity in repeated reasoning); MP.2, MP.5, MP.6 threaded.

Success Criteria — Student Language

• I can name 10 more/10 less quickly and tell how the tens change.
• I can add or subtract a multiple of ten using an open number line or hundreds chart.
• I can explain the pattern: the ones stay the same when I add/subtract 10s.