A second-grade class visits Saint John's Food Pantry each year and spends the morning learning about the needs of the community. Then students pitch in and help the staff for a few hours. When the children return to school, they create signs advertising a canned food drive, and they place collection boxes at various locations around the school. During the course of several weeks, the cans are collected and brought into the classroom, where they begin to stack up, and stack up, and stack up. Before long, cans are everywhere! The authors decided that the abundance of cans would be a good opportunity for a hands-on approach to a math problem. The concept of arrays was not one of the goals when they thought about using cans to design a worthwhile math task. The authors wanted their students to progress from counting objects by ones toward arranging and structuring equal groups of objects and counting them as sets. They posed an open problem that required students to use cans as manipulatives so they could explore different ways of arranging them to make them easier to count. The authors were surprised when students not only placed the cans into equal groups but also began creating arrays. This article explains how the second graders arranged concrete objects (cans) to solve an open problem. The authors examine the various solutions that students used, including the creation of equal groups and the spatial structuring of arrays.