Lesson plan: CECsci.143

May 1994

These lesson plans are the result of the work of the teachers who have attended the Columbia Education Center's Summer Workshop. CEC is a consortium of teacher from 14 western states dedicated to improving the quality of education in the rural, western, United States, and particularly the quality of math and science Education. CEC uses Big Sky Telegraph as the hub of their telecommunications network that allows the participating teachers to stay in contact with their trainers and peers that they have met at the Workshops.

AUTHOR: Janet C. Duncan, Meadow Glade School Battle Ground, WA

GRADE LEVEL: Appropriate for grades 5-8.

OVERVIEW: The purpose of this activity is twofold. Used at the beginning of the year, it introduces the structure and function of a dichotomous key preparatory to asking students to identify plant and animal specimens. It also reinforces the idea that there are many "right" answers in science.

OBJECTIVE(s): Students will be able to:

  1. Classify "specimens" (in this case, potato chips) according to observable characteristics.
  2. Prepare a "key" showing their classification system.
  3. Use their key to identify a specimen.
  4. Recognize the validity of classmates' classification systems.
  1. Eight bags of potato chips selected for differences in observable characteristics (i.e. color, texture, brand name, flavoring, etc.)
  2. Chalkboard or overhead projector for recording class key.
  3. Representative samples of each type of chip in labeled plastic bags. (Quantity determined by number of student groups.)
  4. Paper and pencils for student group recording.
  1. Display bags of potato chips and discuss their similarities and differences.
  2. Ask volunteer to divide chips into two groups using an observable characteristic (i.e. flavored/not flavored).
  3. Record results of first division.
  4. Continue to divide groups of chips, using a different characteristic each time, until only one bag of chips remains in each group. Continue recording results.
  5. Using the class key, identify "unknown" chips.
  6. Divide class into groups of four to six students.
  7. Provide each group with a sample set of chips.
  8. Ask each group to devise and test a dichotomous key that is different from the class key.
  9. Record and share results.
  10. Eat the chips!
  1. Repeat activity with other objects such as candy, shoes, etc.
  2. Share story of potato chips resulting from "mistake." ("Mistakes that Worked" by Charlotte Jones)
  3. Introduce and use plant and animal keys.
                     orange    (Party Pride Barbeque)
                     not orange (Party Pride Sour Cream)
Chips in box
                     ridges (Bell Dip Chips)
             not flavored
                     no ridges (Party Pride Potato Chips)
             ridges (Nalley's Dip Chips)

Chips in bag
                     not "gourmet" (Lay's Potato Chips)
             no ridges
                                   salted (Kettle Chips
                                    unsalted (Kettle
                                      Chips Unsalted)
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