This article is in the October 2014 edition of The Science Teacher. The author engages students by posing the question of whether the leaves at the top of a tree are different from the leaves at the bottom of the tree. The students discuss what environmental differences might be at the top versus the bottom of a tree. The teacher is encouraged to assist the students in thinking about light availability, temperature and water loss. The students are then asked to formulate a hypothesis relating to differences between the groups of leaves using the “if- then” format and to provide an explanation as part of the hypothesis. The lesson engages students as they collect leaves, use measuring tools and proper units, work with microscopes, collect data, analyze their data, and share their data with classmates as they work to evaluate their hypothesis. The students use all of these skills to analyze characteristics of tree leaves and compare their data to the leaves ecological performance. Students have an opportunity to conduct an investigation in the same manner that scientists do. The students and the teacher go outside to cut and collect leaves and make other observations of the trees in the area. After returning to the classroom students examine leaves for differences in leaf surface area, thickness and stomata density and are challenged to construct a data table to organize the various characteristics observed. Students are encouraged to work in small groups to record weights, trace their leaves, make a cut out model and learn to use a modified formula for leaf density. This formula that relates the surface area, weight and thickness of leaves is used by botanists to compare their leaves. Students make molds of their leaves using clear nail polish and tape to help in determining stomata density. Using microscopes, students examine their leaf molds and count the number of stomata within the field of view. Class data are collected and compared. Additional supporting resources for this article are provided at https://www.nsta.org/highschool/connections/201410Instructions.pdf. This lesson is intended and appropriate for high school students.