Lesson objective: Understand that the metric system is related to the base 10 place value system and that structure can be used to convert units of metric length.

Students bring prior knowledge of place value from 2.NBT.A.1.A. This prior knowledge is extended to the metric system as students convert metric units of length from larger units to smaller units. A conceptual challenge students may encounter is thinking that larger units give larger measures.

The concept is developed through work with a place value chart and a metric chart, which help show how the two systems are related.

This work helps students deepen their understanding of operation because they convert larger units of measure to smaller units using the concept that a digit in one place is ten times larger than in the place to the right.

Students engage in Mathematical Practice 7 as they use the place value tables to look at the value of one column or "place" and see how that relates to the value of the column to the right.

**Key vocabulary:**

- centimeter
- conversion
- gram
- kilogram
- kilometer
- liter
- meter
- metric
- milliliter

**Special materials needed:**

- unit cubes
- rods
- flats