Lesson objective: Understand that when the place value extends to thousandths, the structure does not change.

Students bring prior knowledge of base-ten place value understanding from 4.NBT.A.2. This prior knowledge is extended to the new concept as students discover that they can apply the pattern in our base ten system to read and write decimals to the thousandths using base-ten numerals, word form, and expanded form. A conceptual challenge students may encounter is that a flat can be assigned a value and is not always assigned the value of “one”. This means that the blocks representing the value of “one” may change.

The concept is developed through work with base ten blocks, number line, and the place value chart, which provide a representation and support the idea of a consistent pattern in the structure of the base ten number system.

This work helps students deepen their understanding of equivalence as they discover that ten thousandths are equivalent to one hundredth.

Students engage in Mathematical Practice 7 (Look for and make use of structure) as they analyze the consistent structure of a place value system through visual representations.

**Key vocabulary:**

- decimal
- digit
- hundredths
- tenths
- thousandths
- value

**Special materials needed:**

- base ten blocks
- number line
- place value chart