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Brian's Class Materials- FALL 2009 - SEYS 362

SEYS 362 Home

Queens College/CUNY
Education Unit
Fall 2009

Title : Dichotomous Key Delights (Mystery Leaves)
Grade levels : middle school and junior high school, grades 6-9

Subject areas : Biology, Living Environment

Instructional objectives :
  • Students will be able to use an online interactive key to identify common trees
  • Students will be able to use print copy of a dichotomous key to identify trees by their leaves
  • Students will understand why taxonomy and identification of trees is important


  • zip loc bags (4)
  • 1 specimens of dogwood (branch with leaves attached)
  • 1 specimens of pine (branch with leaves attached)
  • 1 specimens of magnolia (branch with leaves attached)
  • 1 specimen of sugar maple (branch with leaves attached)
  • Tree Finder by May Theilgaard Watts (12)
  • computers connected to the Internet with web browsers
  • hand lenses (12)
  • pencils (15)
  • lined paper to record observations, sketches
  • computer for the teacher with projector and screen

Safety precautions :

Mention that some plants are poisonous. Show students images of poison ivy, poison oak, and poison sumac. If you are not sure, ask the teacher before touching it,

What poison ivy looks like:

Poison ivy in summer:

Outsmarting poison ivy and its cousins:

Images of poison ivy, poison oak, and poison sumac:

Procedure :

  1. Motivation: Why is it very important to be able to identify plants?
    • Poison ivy
    • poisonous plants
    • edible plants
  2. Students should then work in pairs or groups of three to answer the following discussion questions:
    • Why is it is important to be able to identify trees?
  3. After the discussion have the students visit a web site with interesting information about trees:
  4. Tell the students that today we will be identifying some mystery leaves and after that we will start identifying all of the trees in our school surroundings. This will be the first stage in doing a comprehensive nature study of the school's surroundings. The first step is learning how to identify trees.
  5. Each group should collect a zip loc bag that contains mystery leaves attached to a branch. Their task is to use the Tree Finder by May Theilgaard Watts to identify their mystery leaf. Once you have finished exchange leaves with another group. Don't tell other groups your results until everyone has had a chance to key out all four leaves.
  6. The second activity will involve using an online interactive nature guide to key out trees. Visit the following web site and then click on IDNature Guides, then on Trees, Shrubs & Vines , North America and click on the Help link to learn how to use the web site.
  7. Go outside and pick at least three different trees that have different leaves from the mystery leaves. Make a sketch of your tree, its leaves and bark, and record detailed observations. You can bring a small sample of leaves on a branch but please make sure not to damage the tree. You will use this information when you are back in the lab to identify your tree. If there is a label and sign on your tree please do not look at it now. Later you can go back outside and check your answer.
  8. After all groups have finished, go over the identify of the mystery leaves. If anyone had problems with the key, they can check the mystery-leaves-hints web page.
  9. At the end of the class, discuss the following questions:
    1. What have you learned about trees and leaves?
    2. Which method was easiest to use, the online interactive nature guide of the printed guide?
    3. How could you make a key to help people identify the plants in your school environment?

Hints:  Please do not look at this until after you have keyed out your mystery leaves