Lesson objective: Understand that decimals can be compared.

Students bring prior knowledge of comparing whole numbers from 4.NBT.A.2. This prior knowledge is extended to decimals as students compare decimals written to the thousandths place. Common misconceptions students may demonsrate are thinking that a digit holds the same value, no matter its place value *or *that the more digits a number has, the greater its value.

The concept of comparing decimal values is developed through work with number lines, which show the relationship that exists between different place values, and through area model representations.

This work helps students deepen their understanding of number because it focuses on relationships between different place values when comparing decimals.

Students engage in Mathematical Practice 7 (Look for and make use of structure) as they use number lines to compare decimals. Students engage in Mathematical Practice 6 (Attend to precision) as they deconstruct tenths into hundredths and thousandths and explain their reasoning using number lines to compare decimals.

**Key vocabulary:**

- area
- area model
- compare
- decimal
- digit
- equal to
- greater than
- less than
- place value
- tenths
- hundredths
- thousandths
- value

**Special materials needed:**

- Blank number lines for student use as needed
- Decimal Area Model Templates as needed