This PDF document discusses a field activity for K-12 students. The purpose of the activity is to observe type and cover of clouds including contrails. Students will observe ten types of clouds and how many of three types of contrails are visible, how much of the sky is covered with clouds, and how much is covered by contrails. The PDF is an instructor guide with detailed advice for administering the activity and data sheets. Educational levels: High school, Intermediate elementary, Middle school, Primary elementary, Undergraduate lower division