K-2 lessons: students learn about tree structure and function and how different tree species in an area support other kinds of life. They develop skills in scientific classification, observation, reasoning, and modeling. 3-5 lessons: students learn about how trees defend themselves and how they benefit humans (focusing on tree-derived herbs and spices). They develop skills in explaining reasoning through arguments based on evidence, using observations to make assessments, and generating solutions to problems within constraints. 6-8 lessons: students learn about trees'' role in the carbon cycle and how human activity related to trees can either drive climate change (deforestation and burning of fossil fuels) or counter it (planting and ensuring the sustained health of trees). They develop skills in systems-thinking, data interpretation, tree measurement, and carbon calculation. Supplementary lesson materials provide “environmental champion” challenges to encourage students to develop environmentally-positive habits, and also include information on stewardship practices of local Indigenous Peoples.