Tracy Sola has been an educator for 18 years; she spent six years in a kindergarten classroom and the next 10 years as a middle-school math teacher and K-8 grade math coach.

At the time of the documentation of this lesson, she had been the full-time, assistant director of the Silicon Valley Mathematics Initiative for two years. She had previously worked on multiple occasions with the first-grade students in this Eliot Elementary School classroom in the Gilroy Unified School District (Gilroy, California).

In this lesson, Sola works with first-grade students on a formative re-engagement lesson about non-standard measurement. She challenges the students to use non-standard measurement items — cubes, their feet, paper clips, their hands — to measure something in the classroom. When students discover that they have different answers after measuring how long things are, she asks them to think about what that means, eliciting ideas about standardization.

The essential ideas of the lesson establish the vocabulary of measurement, including comparative language like “long and short” that can be used to compare two or more objects. Later in the lesson, she asks students to use the terms “taller and shorter,” and to discuss how the word shorter is used not only in length, but also in height.