Lesson objective: Measure length with non-standard length units.

This lesson helps to build fluency as students measure length with non-standard length units. Different types of non-standard length units are used in this lesson because it supports how many different things can be used as length units. This work develops students' understanding that length can be measured using non-standard length units.

Students engage in Mathematical Practice #2 (reason abstractly and quantitatively) as they measure with length units and make approximations when the length units and the object they are measuring do not exactly align; Mathematical Practice #5 (use appropriate tools strategically) as they use length units to measure length; and Mathematical Practice #6 (attend to precision) as they work with the non-standard length units to determine the length of the object being measured. Students will make an approximation, or guess, how many length units it will take to span the length of a given object. They will check their guesses by using the length units to measure the object and determine the actual length.

**Key vocabulary:**

- "guess and check"
- length measurement
- length units
- span

**Special materials needed:**

- non-standard length units (e.g. blocks, building cubes, paper clips, etc.)
- items to measure (e.g. dollar bills, notebook paper, strips of paper, table tops, etc.)