The teacher, Maryann, launches the Cubes in a Line lesson by showing her students two cubes and asking the question, “If I put two cubes together, how many faces are there?” We drop in as several students share their responses and the class discussion ensues.

# Expressions/Equations/Equivalence

## Debra’s Question

After small groups share three different equations to determine the number of 1 x 1 tiles needed to form a border for a square pool with side length x, Debra asks, “Are these equations the same?”

## Working Backward

After solving the Growing Dots task, students are asked to work backwards to determine at how many minutes they will have 25 dots, 73 dots, and 99 dots. In this clip, students share how they arrived at their answers.