This Going Green (elem/upper elem) Word Problems is perfect to practice problem solving skills. Your elementary grade students will love this Going Green (elem/upper elem) Word Problems. "We know that, on average, each tree absorbs from 13 to 48 pounds of carbon dioxide per year. We have planted 15 trees. How much carbon dioxide absorption will the trees we’ve already planted enable in the next 50 years?" Five math problems with an environmental theme.