First, students will learn how to convert larger metric units of length to smaller ones. Units of length will include millimeters, centimeters, meters, and kilometers.

Converting metric units of length by Khan Academy

Convert to smaller units (mm, cm, m, & km) by Khan Academy

Next, students will learn how to convert larger US customary units of length to smaller ones. Units of length will include inches, feet, yards, and miles.

Watch these Khan Academy videos:

Next, give your students this challenge:

Light the Lights by NRICH

Conclude by leading this investigation:

Venn Diagram Puzzles

by MathPickle

4.MD.A.1: Know relative sizes of measurement units within one system of units including km, m, cm; kg, g; lb, oz.; l, ml; hr, min, sec. Within a single system of measurement, express measurements in a larger unit in terms of a smaller unit. Record measurement equivalents in a two-column table. *For example, know that 1 ft is 12 times as long as 1 in. Express the length of a 4 ft snake as 48 in. Generate a conversion table for feet and inches listing the number pairs (1, 12), (2, 24), (3, 36), ...*