Lesson 9

The purpose of this lesson is for students to describe the relationship between liters and milliliters and between kilograms and grams, and to express each of the larger units in terms of the smaller units.

In grade 3, students solved problems involving capacity and weight. They may have encountered the units grams, kilograms, liters, and milliliters—both in the classroom or beyond—but have yet to develop a sense of the relationship between grams and kilograms, and between liters and milliliters.

Here, students develop an understanding of 1 kilogram as 1,000 times as heavy as 1 gram, and 1 liter as 1,000 times as much as 1 milliliter. For some students, this may be their first experience with metric units of mass and capacity. The lesson moves quickly to introduce two different sets of measurement units, but students will work with them again in future lessons. Consider offering anchor charts or visual representations to serve as a reference and to solidify the relationships between measurement units.

In subsequent lessons, students apply the understandings from this lesson to solve various problems.

• Gather one or more boxes of 100 metal paper clips, if available. 

• If possible, gather a 1-milliliter medicine dropper, a 20-milliliter medicine dosage cup, a 100-milliliter measuring cup or cylinder, and an empty 1-liter bottle with a line at the 1-liter mark. 
• Obtain 1.5 liters of water or access to a water source.

Students may need to engage with measuring using different units to deepen their sense of relationships. How can you reinforce the work done in today’s lesson outside of math class? How can you incorporate opportunities to measure weight and capacity in science or other subject areas?