Discover how percents and proportions help explain issues like climate change, composting, and zero waste in this video from KQED. In the accompanying classroom activity, students estimate the percentage of various types of trash that they generate (e.g., paper, plastic) and calculate the pounds of each based on the United States daily average of 7 pounds per person. They display these figures in a pie chart and consider how the chart would change if they generated less trash. To get the most from this lesson, students should have some prior experience calculating percentages.