Unit Plan 26 (Grade 4 Math): Compare Decimals—Place-Value Reasoning

Focus: Compare decimals to hundredths using place-value understanding; record comparisons with symbols (>, <, =) and justify with models, number lines, and the same whole idea.

Grade Level: 4

Subject Area: Mathematics (Number & Operations—Fractions: Decimal Notation)

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

I. Introduction

Students learn to compare two decimals to hundredths by analyzing digits in the tenths and hundredths places, renaming with trailing zeros (e.g., 0.5 = 0.50), and using place-value charts, 10×10 grids, and the number line. They explain and record comparisons with >, <, and =, always referencing the same whole.

Essential Questions

• How does place value help me decide which decimal is greater?
• Why do trailing zeros (e.g., 0.50) not change a decimal’s value?
• How do representations (place-value charts, number lines, grids) strengthen my justification?

II. Objectives and Standards

Learning Objectives — Students will be able to:

1. Compare decimals to hundredths by analyzing tenths then hundredths and by using benchmark values (e.g., 0.5, 1.0).
2. Record comparisons using >, <, and =, and explain why the statement is true using a model or number line.
3. Rename decimals with trailing zeros (e.g., 0.5 = 0.50) and explain why the value stays the same (same whole).
4. Solve real-world measurement and money problems requiring decimal comparison; justify with place-value reasoning.
5. Evaluate reasonableness and correct common errors (misreading digits, misaligning the decimal point).

Standards Alignment — CCSS Grade 4

• 4.NF.7: Compare two decimals to hundredths by reasoning about their size; recognize that comparisons are valid only when the two decimals refer to the same whole; record comparisons with the symbols >, =, and <, and justify the conclusions (e.g., with a visual model).

Success Criteria — Student Language

• I can line up decimal points and compare tenths then hundredths.
• I can use >, <, and = correctly and explain my choice with a model or number line.
• I can show that 0.5 and 0.50 are the same value (same whole).