Keywords: alternate, opposite, whorled, simple, compound, leaf arrangement; Lesson Plan Grade Level: ninth through twelfth grade; Total Time Required for Lesson: minimum 30 minutes, may expand to two or three class periods according to depth and amount of repetition to be sure students truly understand the concepts; Setting: This activity probably works best outdoors, ideally in an open area adjacent to a variety of different tree species. It can be adapted to areas of less species diversity or even inside a classroom if necessary by bringing a variety of different samples to the program site.

Goals for the Lesson

  • Have students understand concepts that are the foundations to identifying trees.
  • To allow students to have fun using their bodies to "act out" the positions of various leaf arrangements and structures to enhance their cognitive recall of these concepts.

Materials Needed

  • trees or leaf samples

State Standards Addressed: Environment and Ecology (4.2); Renewable and Nonrenewable Resources

Teaching Model: a variation of The Concept Attainment model.

Subjects Covered: life science, agriscience, biology (dendrology)

Topics Covered: Introductory Dendrology including:

  • leaf arrangement and structure
  • simple vs. compound
  • alternate, opposite, whorled



I developed this while working with third through fifth grade students at an activity we call agriculture awareness days. I was having difficulty getting across some of the basic concepts of leaf arrangement to the students. I know from my own learning style and teaching experience that I learn best when actively engaged in a learning activity that involves more of my senses than just hearing and sight.

When I first stumbled upon this several of my 9th grade students that were assisting me with the program indicated it made it easier for them to remember as well. When one of my best 11th graders stopped by our station later taking some photographs, she too commented that she thought she would have learned the concept better. I share this to tell you I believe this activity will have universal appeal to students of all ages.

  1. Introduce the terms petiole or leaf stem, and leaflet. This leads to a discussion of simple as compared to compound leaves.
    • Start by helping the students define the five basic terms involved in attaining the concepts of leaf arrangement (alternate, opposite, whorled) or leaf structure type (simple or compound)
    • Depending upon the age group the lesson is targeted for you can use more technical terminology to get the ideas across. Younger students may react best by being shown an example of an opposite leaf and then multiple examples (some of which are opposite and some of which are not) and asking the students to make a judgment as to whether they are opposite or not. Once the majority of the students are correctly identifying the trees with opposite leaf arrangement you can begin to draw out of them the characteristics that describe a tree that has opposite laves. This is the basis for the concept attainment teaching model.
    • For older students I may start with the more detailed description, a tree with two leaves growing directly across from one another at the same node (growth point) on the stem. Once they seem to have the idea verbally I still check for understanding by showing them a number of samples and asking them to make a yes or no decision is it opposite or not?
    • This would continue for each of the terms.
  2. Next introduce an acronym for remembering all of the important families of trees in Pennsylvania that have opposite leaves: MAD Horse.
    • Maple
    • Ash
    • Dogwood
    • Horse chestnut
  3. Going back to the concept of simple and compound. Tell them that the maples and the dogwoods are both opposite and simple while the ashes and the horse chestnut are both opposite and compound.
  4. Now the kinetic part of the lesson begins. Instruct the students to think of their arms as the petioles Leaf stems) and their bodies as the main twig. Then ask them to first imagine and then show me what a tree with opposite leaves would look like (arms thrust straight out from shoulders). Next we do a tree with alternate leaf arrangement. (One arm down closer to the waist and one near the shoulder).
  5. The instructor can also position themselves in "opposite and alternate" positions and have the students shout out the correct response. This helps them to process the information both ways from term to concept and from term to concept.
  6. Next call out a species or family and see if they can quickly get into the correct position (opposite or alternate)
  7. Then, to simulate simple and compound, remind them that simple leaves have only one leaflet per petiole so we signify this by pointing (1) with the index fingers. Compound leaves are shown with all of the fingers and thumb outstretched in an open hand since there are multiple leaflets per petiole making up a compound leaf.
  8. Now we can combine the two concepts by calling out species and seeing how quickly students can get both the leaf arrangement and the leaf type correct.
  9. For the grand finale see if they can do the Catalpa (both arms outstretched and tongue sticking out to denote whorled leaf arrangement).


  1. There will be immediate feedback as to the level of understanding of these basic concepts as the instructor calls out the various families o species names and watches the students put their arms and hands in the correct positions
  2. The level of sophistication or simplicity can be geared to the age and knowledge level of the students. These are concepts that can be built upon. Students seem to respond well to being increasingly challenged as their experience base develops.
  3. There can also be a formal testing of the concepts (see examples in the appendix).
  4. I have seen a definite connection between the kinetic movements and increased learning. I hope you are able to try this and find similar results.


Department of Conservation and Natural Resources, Bureau of Forestry. Common Trees of Pennsylvania. 8100-BK-DCNR 1906 ( available for free through your County Service Forester).


Appendix A: Basic Dendrology Terminology Handout


Bob Lauffer, Garden Spot High School