Maine’s forest industry annually harvests up to 7 million cords of wood to build homes and make products. But only 25 percent of students in biology courses on six University of Maine System campuses knew incorporation of CO2 gas from the atmosphere into molecules by leaves is the process that contributes most to increase timber biomass. Faculty members identified this and other misunderstood concepts involving light, energy, carbon dioxide and nutrients, and developed an active-learning lesson about trees and other regionally relevant photosynthetic organisms, including potatoes and kelp. After the lesson, 92 percent of students knew the answer and demonstrated short- and long-term knowledge gain, says Michelle Smith, associate professor in the School of Biology and Ecology. Actively engaging students in STEM classes increases their performance and decreases their failure rate when compared to courses where lecturing is the instruction method. It also narrows the achievement gap for first-generation students, and nearly 42 percent of full-time students in the system fit that description.