The purpose of this activity is to measure ozone concentrations at ground level. Students deploy a strip of paper that changes color in the presence of ozone. They use an ozone reader to determine the amount of ozone in ppb as indicated by the color change of the paper strip. Intended outcomes are that students will learn to measure the concentrations of ground-level ozone in the atmosphere and to observe changes in the concentrations over time. Supporting background materials for both student and teacher are included. Educational levels: Primary elementary, Intermediate elementary, Middle school, High school