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A Mini-Lesson



Video Notes Worksheet


Larry Flammer


Variations and Natural Selection
 NEW ARTICLE: Common Misconceptions about Natural Selection. Go to our Evolution Introduction page, scroll down to bottom of page for "A Few Very Common Misconceptions" and a link to the excellent article that exposes a number of widely held misconceptions, with clues for correcting them (June 2009).


Video showing recent field work on a twenty two-year study of finch beaks on a small island in the Galapagos, showing natural selection clearly operating in the wild. Includes vignettes of Darwin's life, and the Grant family working and living on the island. Excellent video. Video-notes worksheet helps to guide viewing for students, and facilitates subsequent discussion.


1. Traits are usually favored by natural selection only when they result in more reproductively successful offspring.

2. Natural selection can be observed in nature to produce significant changes in the characteristics of a species.

3. Elements of the environment play a clear role in giving direction to selection.


 Video: "What Darwin Never Saw", from the PBS series "The New Explorers", with Bill Kurtis. This program aired on Public Television in October, 1995. Call 1-312-951-5700 (Kurtis Productions) to order the video ($20); ask for Rebecca Kelly. Or, write to Kurtis Productions (attention Rebecca), 400 W. Erie Street, Suite 500, Chicago, IL, 60610. Send check for $20 payable to Kurtis Productions.


 (see end of lesson for the formatted handouts).

Copy of "Video Notes" for each student.




This 50 minute video could be shown as a very engaging introduction to evolution in general, or to natural selection in particular. Or, it could be shown as part of your wrap up and summary of your work on natural selection.

When I use the film, we have already studied the nature of science, so my students should know the difference between a theory and a hypothesis, and that a theory is a concept in which we have a high degree of confidence, due to considerable supporting evidence, so to say "only a theory" reveals a popular misuse of the word, incorrectly suggesting that it is just a tenuous idea.

I also will have covered a brief overview on the diversity of life and the formal elements of classification.

In my introduction to evolution, I make a point of going over several things that evolution is NOT, primarily to dispel some of the popular myths people often assume about evolution (see my unit outline in the outline section on this site). I will have clearly distinguished between the "origin of life" and the "origin of species", and have pointed out that biological evolution is NOT about the origin of life, but it IS about the origin of species. There is a popular confusion about these two ideas, assuming they are the same, no doubt stemming from the biblical account that all life, in all its present forms (species) was created at one point in time. With the clear evidence that many different forms have come and gone over long periods of time, evolution attempts to account for this, leaving the formation (creation?, beginning?, origin?) of first life as a separate issue.

I will also have introduced the class to Charles Darwin, his life and contributions, using film, slides, text, and bulletin board, all as part of my formal introduction, early in the course, to the general ideas of evolution and natural selection.

Against this backdrop, the video offers an excellent opportunity for students to see scientists at work in the field (as opposed to a "lab"), testing ideas, and showing how careful observations can reveal telling patterns. It also conveys some of the "humanness" of scientists, ordinary people, with families, doing extraordinary things. Students can identify with this, and perhaps be inspired to do this kind of work.

VIDEO NOTES: I have found that students tend to pay closer attention to a video if they are looking for particular bits of important or unusual information, as long as there are not too many little "bits", and they have substantial time to just watch and enjoy. "Video Notes" also provide a convenient vehicle to clarify certain important points presented in the video, but possibly done too quickly or not as clearly as you would like. Finally, the notes are useful for initiating discussion after the video, especially if this must be put off to the next day (since the film takes about a period just to watch).

I often ask students to add on the back any questions that come to mind ("always watch with a questioning attitude"), or points to discuss. In addition, I may ask them to "rate" the video, and to indicate what was most memorable. I collect the papers at end of video, and quickly check them over, looking for their comments on the back. The next day, I use some of their questions or comments to initiate discussion.

A key to the "Video Notes" follows the worksheet below.

I highly recommend that you read the popular book which covers this study: The Beak of the Finch by Jonathan Weiner (Knopf, 1994, $25), a Pulitzer Prize winning book about the Grants and their work with the finches, as featured in the video. This should be in your school library, as well. For any students wanting more of the "meat" of the study, encourage them to read it, too.


An excellent alternative lesson, built around the Grants' finch sudy, with data,, a lesson, and a key, can be found on the PBS-Evolution site.

For a good overview of Natural Selection, and an alert to some common misconceptions about it, take a look at the handy summary: "Comparing Evolution Mechanisms" near the bottom of the "Introduction to Evolution" page. Darwin's and Lamarck's essential elements are compared, and a few common misconceptions are clarified. Scroll down to download the PDF file of this information.

Here are some more online lessons and related resources:
Teach Evolution and Make it Relevant
Clipbirds: Natural Selection of Acquired traits and Allopatric Speciation
My Science Box (with links to the following sites):
Finch Beak Data (Teachers' Domain - free registration)
What Darwin Never Saw, Chicago Academy of Sciences
Case Study (Original Data from the Grants' Study) - Prentice Hall


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: Larry Flammer, 11/95

2. Reviewed / Edited by: Martin Nickels, Craig Nelson, Jean Beard: 12/15/97

3. Edited / Revised for website by L. Flammer 4/16/99


 The following is a useful worksheet for students to complete while watching the video, to help focus and direct their viewing. A KEY follows, for teacher use, or for use by students as a self-check. PDF VERSION CAN BE ACCESSED AT BOTTOM OF PAGE.

 Name___________________________________ S.N._____ Date_________ Per.____


VIDEO NOTES: "What Darwin Never Saw" (The New Explorers series, w/ Bill Kurtis)


1. In the first few minutes of the film, the narrator, Bill Kurtis, uses two phrases which are technically incorrect in their biological context, and you should recognize this from our course so far. How should they have been worded to be more accurate?:

A: He said: "...the finches held the secret to the origin of life." He should have said:

"...the finches held the secret to the origin of ___________"


B: He said: "...but it was only a theory." He should have said: "...but it was.._______________________"


2. What did the Grants do when they went ashore on the island to be sure nothing was brought onto the island from the "outside world" (no insects or other creatures which might disrupt the natural habitat on this isolated island)?


3. What is the main enemy of the of the finches on Daphne Major Island? _______________


4. What is the finch on Daphne which digs into cactus blossoms? __________finch


5. What major biological process have the Grants seen TWICE during their 22 years of studying the islands?


6. In what year did the Grants first come to the island? _________


7. The three questions they were trying to answer by studying the finches were:

a. Do species compete?

b. Why are some populations so variable?

c. ________________________________


8. Why was Daphne Island chosen? ______________________


9. One species of finch was G. scandens (Cactus Finch). The other species was G. fortis. What is its common name:


10 How many finches did they find and band on the island? __________


11. When binoculars are reversed, what can they be used for? _______________


12. Your choice: some interesting facts given about Darwin in his experiences on the Beagle, tortoises, etc:




13. What did the Grants find when it didn't rain for 18 months?_______________________________


14. They found that natural selection operates under.._______________ conditions.


15. Birds with ____________ beaks tended to survive the drought best. Why?



16. All but about ________% of all species which have ever existed are extinct now, [so what % are extinct?___]


17. The Grants measured the beaks of the next-generation birds (from those which survived the drought). What was the size of those beaks (compared to the average size before)?


18. What surprising conclusion did this observation provide good evidence for?



19. Which finches survived best after it rained so heavily (for 8 months)?______________ Why?


1. A) "...species"; B) "...a possible hypothesis"

2. rinsed everything in seawater

3. weather (not owls)

4. Cactus

5. natural selection (or evolution???)

6. 1973

7. c) How are species formed?

8. simple, small (100 acres)

9. Medium Ground Finch (Geospiza fortis) [see The American Biology Teacher, April, 1993, p.243 presenting this and other examples of natural selection]

10. about 1000 finches

11. microscope

12. [open] [show some Wedgewood pottery, if you can]

13. 400-500 dead finches found (mostly G. fortis)

14. stressful (specifically draught conditions in this case)

15. large; They can break into large seeds that smaller-beaked finches can't open.

16. 1% [so 99% extinct!]

17. larger (3-4% deeper)

18. Evolution proceeds much more rapidly than Darwin suspected.

19. smaller finches



Video Notes: "What Darwin Never Saw", plus Key


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