Erika Isomura teaches fourth and fifth grade at Glassbrook Elementary in Hayward, California; in these videos, 22 of her 30 students are fifth graders. Depending on the mathematics content and her formative assessment of her students, at times she combines her students for mathematics lessons and at times she differentiates between grade levels by using mixed groups.
In the weeks preceding this lesson, Erika realized she needed to address some confusion she had diagnosed in her students around fractions — specifically, needing to develop greater consistency between their numerical and visual representations: “If this is my whole and this is a fourth, then on your next picture this is still the whole and this is the fourth.”
She also documented a lesson later in the year focused on representing decimals.
In this lesson, she connects her students’ work with prior “mentor problems” — string problems (e.g., seven lengths of rope that are each 2/3 of a foot long) and recipe problems (“I want to make this recipe five times and this is the quantity of flour I need,” or "I was going to make this recipe but I decided only to make 1/4 because that's just me.”)
She hoped to build her students’ capacity to apply a bar model independently to novel problems with fractions.