Students use materials from around the room of their choice to represent an assigned teen number. Students were asked to be efficient mathematicians and to make their representation in an organized fashion. The goal was for someone to walk in the room glance at their collection and know how many were there without counting by ones. We define teen numbers as a group of 10 and some ones. Students were able to walk around the room and take a gallery walk to see how others created the representations. After the gallery walk, students had the opportunity to revise their thinking and to make their representation more efficient/organized.
