© 1999 ENSI (Evolution & the Nature of Science Institutes) www.indiana.edu/~ensiweb
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A Mini-Lesson


Cladistics Is a Zip...Baggie

An interactive class demo of cladistics

 

John Banister-Marx

EVOLUTION

Classification

 SYNOPSIS

A series of nested plastic bags is used as a 3-dimensional Venn diagram to illustrate the hierarchical grouping of organisms based on their shared derived characters, thus forming the basis of a cladogram.

 CONCEPT

The groups-within-groups hierarchical pattern of Linnaean classification is a result of both extinction and branching from common descent.

 

MATERIALS

  PDF files of the following pages are formatted to fit on single sheets. However, retrieving them requires that the Adobe Reader be installed on your computer. Click on PDF to access those files AND a link to Reader.

The following pages are in html, condensed as much as possible, but the first two may require printing onto 2 pages for each. Just click on the file name to see it. Click on the "Back" button of your browser to return here.

1. Cladistics Is a Zip...Baggie (General Instructions, prep, procedures)

2. What the Heck IS Cladistics? (Summary information about cladistics)

3. Animal Names (4 sets of 7 animal names on one sheet, to be cut apart)

4. Nested Bags (diagram of 7 nested zip baggies, for overhead display)
In PDF format only.

See in Extensions & Variations (below) the special MIDDLE SCHOOL version developed with handouts (by ENSI teacher Karin Westerling) - Go there for the .

 STUDENT HANDOUTS  none

 

TEACHING STRATEGY

 Click here to see "Cladistics Is a Zip...Baggie" preparation and procedures.

Teacher: You can use the page showing the 7 nested zip lock baggies to make an overhead to use in your before and/or after-lab discussion (also in pdf format)

This technique can be adapted to other labs on cladistics that use a similar format to the one being used in this simulation. The ENSI-SENSI site (http://www.indiana.edu/~ensiweb)will have similar labs that deal with other groups of organisms, e.g., primates, in the near future. They will be in the Evolution Lessons, Classification section.

This activity was demonstrated in Reno (1998 NABT Convention) using nested cans. These work fine, too, especially as a demonstration. You might try these before, or after students do the lesson with bags. Nested sets of cans for everyone are a little harder to collect and store, and noisier, too!

 EXTENSIONS & VARIATIONS

Better Version for MIDDLE SCHOOL: ENSI Fellow, Karin Westerling (ENSI '92), has developed a more structured and very clever version of this lesson, perhaps more appropriate for middle school Life Science. CLICK HERE for the 11-page pdf file includes 7 pages for the student material, and the last 4 pages (8-11) have a sample of responses that should be expected, essentially. The student pages include a choice of two Venn diagrams, only one of which would be provided to each student (or team): one colored and one in shades of gray (if color copier not used). Another page (6) has three strips that should be cut apart, one per student or team of students.

To save time, the 8 cards on page 3 could be cut apart and provided, one set per student or team, along with a strip from page 6, one of the Venn diagrams, two pages of instructions (1-2), and the discussion questions (page 5).

 RESOURCES

1. See the article by Andrew J. Petto: "The De-riving Force of Cladogenesis"
A clear and concise explanation of the concepts and terms of cladistics. This could be copied and printed as a student handout. (Click on the "Back" button of your browser to return here.)

2. Be sure to see the UCMP site for more extensive coverage of phylogeny, cladistics and systematics.

3. The UCMP (University of California Museum of Paleontology) has an excellent presentation of cladistics, phylogenies, and modern systematics (what, why, when, and how). Take a look at it: (<http://www.ucmp.berkeley.edu/exhibit/phylogeny.html>).

4. See the excellent online tutorial by the UCMP: "What did T. rex taste like?" It makes an excellent introduction to classification, phylogenetic trees, and cladistics. This could be given as a homework assignment (online).

5. For an excellent tutorial to introduce phylogenetic (evolutionary) trees, see our review of an article in the American Biology Teacher.

6. Get the excellent article "Why Cladistics?" (Gaffney, E.S., L. Dingus, and M.K. Smith, Natural History Magazine, 6/95, pp. 33-35.) from your public or university library, and have students read and discuss it. See the Mini-Lesson on this site for sample Reading Guides for this article.

7.Get the essay by Stephen Jay Gould "What, If Anything, Is A Zebra?", found in the author's book Hen's Teeth and Horses' Toes, 1994. W.W. Norton & Co. (available at discount from NCSE books). Have students read and discuss it. See the Zebra Mini-Lesson on this site for a sample Reading Guide / Worksheet and key for this article.

8. For an excellent and popular lesson in cladistics, see the Making Cladograms lesson on this site.

 ATTRIBUTION

Some of the ideas in this lesson may have been adapted from earlier, unacknowledged sources without our knowledge. If the reader believes this to be the case, please let us know, and appropriate corrections will be made. Thanks.

1. Original Source: John Banister-Marx (using nested cans) 11/98
Nested baggies version: 10/99 at Ft. Worth NABT

2. Adapted for website by L. Flammer 3/99
Revised 1/00.

3. Middle School Version added 4.10.08 (by ENSI Fellow, Karin Westerling.


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