Tell them to remember the things that made them smile. Explain that it is always best to have an adult pick up these kinds of items because they will know more about what specific precautions may be needed. Have the students verbally generate a list of words describing a park that is clean, and then a second list describing a park that is dirty. Remind the students about their imagined picnic and hike. Each student should draw a picture of what they remember that made them smile.
Extension Take the students outside for a picnic lunch and clean up afterward.
This activity was adapted from Marine Debris Teaching Activities available from the Center for Marine Education.