Lesson objective: Apply knowledge about measuring with length units to measure the length of items in the classroom.

This lesson provides an opportunity for students to apply their knowledge and understanding of measuring with length units to a real-life situation. Students are asked to measure the length of large items within their classroom (e.g. chalkboard tray, base of aquarium, length from desk to door, etc.) with a partner.

Key Concept students will use:

- Length can be measured with non-standard length units.

Skills students will use:

- Students will select a non-standard length unit and an object/ distance to measure.
- Students will line up their selected length unit end-to-end to span the length of the object/ distance they are measuring.
- Students will count the number of length units they used to get the length measurement of the object/ distance.

Students engage in Mathematical Practice #2 (reason abstractly and quantitatively) as they measure with non-standard length units and make approximations when the object being measured and the length units do not exactly align; Mathematical Practice #5 (use appropriate tools strategically) as they use non-standard length units to measure length; Mathematical Practice #6 (attend to precision) as they strategically manipulate non-standard length units to measure the length of a given object or distance. Prompt students to remember to make an approximation, or guess, about the length of the object/ distance and check their guess by doing the actual measurement work.

**Key vocabulary: **

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

**Special materials needed:**

- non-standard length units (blocks, building cubes, paper clips, etc.)
- classroom items for measurement (chalkboard tray, base of something large like an aquarium, designated distance from point A to point B for measurement (indicated with a line of tape on the floor for guidance), the clear surface of a long table, etc.)