Combined Program in Education and Psychology

The University of Michigan, Ann Arbor

2. When the students signaled to the interviewer that they were done reading they took a 5 minute break, left the room to get a drink of water and walked around a bit. When they came back, the interviewer asked the students to write down what they could remember and what they learned from reading the passage.  The two students' verbatim responses to this free recall task are displayed in Table 1.

3.  After the students were done with this recall task, they were asked two questions about adaptation that required them to "go beyond the infuriation given" in the actual passage and transfer or apply the information to a different situation.  The questions were taken from the list of suggested discussion questions in the teacher's manual.  The students' verbatim responses to these two questions are displayed in Table 2. The two "transfer" questions were:

Q1:What if Ann Arbor became very cold and had snow year round like the North Pole? What might happen to the animals that live here now?

Organisms Adapt to Their Environments

  Fossils indicate that changes have taken place in the past, but they do not tell us how.  To find out how changes might have occurred in the past, life scientists study changes in living things.  An adaptation (a'dap ta'shen) is the result of changes in the genetic makeup of an organism.  These changes may be in body structure, body function, coloration, or behavior.  Adaptations allow organisms to survive in certain environments. For example, the anteater shown below lives mostly on insects found in hard-to-reach places. To catch the insects it eats, the anteater has a long, sticky tongue.  An organism whose tongue is not adapted to this type of food searching would find it much more difficult to live on these insects.

  Sometimes an adaptation can involve more than one species.  For example, one species can imitate another species for protection.  The butterflies in the pictures above look alike, but they are different species.  The monarch butterfly, shown on the left, contains a chemical that makes it distasteful to birds.  Birds soon learn not to eat the bad-tasting monarchs.  The viceroy, shown on the right, might taste fine to a bird.  But it looks so much like the monarch that birds often stay away from the viceroy species too.

 

Mutations Can Cause Change

Sometimes changes (in an organism come about through mutations, (myu ta shenz), which are random changes in genes and chromosomes.  Mutations occur naturally in the cells of organisms.  Usually, mutations produce no noticeable changes in organisms.  Some mutations, however, can lower an organism's chances of surviving and producing young.

  The squirrel, shown to the right, is an albino (al bi' no).  Albinos have a mutation in their genes that prevents them from having normal body colors.  This mutation can be harmful to the squirrel since it will not blend with its surroundings.  Therefor, the albino squirrel may be more visible to its enemies.

  Other mutations can be an advantage for an organism.  For example, some mosquitoes sprayed by DDT probably had mutations that enabled them to resist the DDT poison.  These mosquitoes lived and passed their DDT resistance on to their offspring.

 

Natural Selection

Over 150 years ago, an English naturalist by the name of Charles Darwin set off on a voyage around the world.  On his trip, Darwin found organisms that he had never seen before.  Yet he recognized that some of these unknown organisms looked like some of the plants and animals he was familiar with in England.  Through careful observations, Darwin developed an idea that helps explain how groups of organisms change in the theory of evolution.  This idea is called natural selection (nach er el si lek shen).

 There were several observations that led Darwin to the idea of natural selection.

First, Darwin saw that most species produce more offspring than the environment can support.  Notice, for example, the many tadpoles in the picture to the left.  There is only a limited amount of food and space for these developing frogs.  Many will not survive.

   Another observation Darwin made was that the members of any one species are not exactly alike.  The second picture to the left shows adult frogs of the same species.  Notice that some of their body colors are slightly different.

    Darwin concluded that there must be a struggle for existence among organisms, such as tadpoles.  He also realized that certain traits, such as a frog's color, make an organism better adapted to its environment.  If an organism is better adapted, it stands a better chance of surviving and reproducing.  For example, frogs with body colors that most closely match their environment will be better able to hide from their enemies.  These frogs may then survive and produce offspring.  Over many generations, certain inherited traits will be naturally selected by certain environments.

It should be mentioned that Darwin delayed publishing his ideas on natural selection for more than twenty years after his worldwide travels.  In the meantime, another English naturalist, A. R. Wallace, had also come up with ideas about natural selection. In fairness to Darwin, however, Wallace generously waited to publish his views.  Both Darwin's and Wallace's papers were finally presented together at a scientific meeting in 1858.

The organisms you see above are a famous example of Darwin's process of natural selection.  About a hundred years ago, there was a species of moths in England called peppered moths.  Almost all of the peppered moths were light-colored.  When these light-colored moths rested on light-colored tree trunks, they blended in with the tress.  The color made it hard for birds to spot and eat the moths.  However, as more factories were built in England, soot began to blacken the trees.  People soon discovered dark-colored peppered moths on the darkened bark of the trees.  Within 75 years, there were more dark-colored moths than light-colored moths.

The color change in the moth species can be explained by the process of natural selection.  When the tree trunks became blackened by soot, the light-colored moths were easily spotted and eaten by birds.  The few moths with naturally occurring mutations for darker colors blended in with the dark soot on the bark.  These dark-colored moths were eaten in lesser numbers.  They then produced offspring which inherited the genes for the darker color.  These dark-colored offspring also were eaten in lesser numbers. Gradually, the populations changed from mostly light-colored to mostly dark-colored moths.

The students read the passage from the textbook, which included all the pictures, diagrams, etc. LeVon Balzar et al. Life Science. Copyright 1987, by Scott, Foresman and Co.  Reprinted by permission.

1: OK. This is the last thing we have to do.  When you read these pages in the textbook, could you tell me what you were doing?  When you read these 4 pages, what were you thinking?  Start at the beginning and tell me everything you did.

C: I, um, I started reading and um, some of the definitions of the words in the black I couldn't understand.  So I went over again and started from the beginning-started reading again.  And with all the examples-like "adaptation"—I couldn't understand the meaning so with the examples—I used the examples to understand how, what it might be.  I had an idea of what it was.  Um.  There was enough information I already knew.  Before I started.  I just used the context clue to understand the word and thought of some more examples that might be possible.... Um, like on this page, about Charles Darwin, I already knew about Charles Darwin, so, it helped me understand all the changes and how evolution occurred, um, and how the species may be different from the young ones.  All the explanations—I understood these 2 pages really well.  Better than these 2. I didn't really know them that well.  Um. . . are you still... all I did was try to take the context clue and put it all together in my mind and see what I could do.  And some things I still don't understand, but most of it I do.

I:  OK. You said that you made some of your own examples, after you read about a definition. You made some of your own examples.  Why did you do that?

C:  Oh, well, using this example, if I could make some more examples it would make me understand more.  Then I would know, "Yes, I do understand this."  Because just using the example, they give a really good example about insects--using that, I thought of some different examples, I thought.  And then if I thought I got it right, then I know that I understand the whole thing.

I:  When you were writing all those things you could remember, tell me what you were thinking then.

C:  I was trying to remember all the examples mainly.  And from—because I didn't remember the exact definition of the word, so, just using the examples, I just put it in my own words.  What it was.  And I gave examples also.  So if I don't understand, if I don't know the definition, I look back at the examples on the paper and then try to see.  So...

I:  Good.  When I was asking you about Ann Arbor, and the coyote in the desert, what were you thinking about when you were answering those questions?

C:  ... Um . . . I thought about, . .first of all, I wanted to think about what you'd asked.  And understand what you was ask--what you were asking me. And then I thought about all the things I read and if there was any relationship between the question you asked and the thing I read.  I couldn't, I couldn't really mix them both up­the examples from the book and the questions up that well.  I don't know why, but I just couldn't make them up that well.  My answer might not have been that good.  If I'd understood them that well.

I:  You said that you tried to make connections and this between what you read and the questions I had--why did you do that?

C:  Because, um, in the second question the word "mutation" came up.  So I knew there was something about mutation in the book so I thought about all the things that were in the book and it helped me understand what mutation had to do with the coyote and with the change.

I:  And then you said that you spent some time trying to understand what my question was—why did you do that?

C:  Um ... just to clear myself up about what you were asking.  Cause at first I didn't understand.  Then I looked at the question, stared at it, and think about what it's really asking me.  I cannot just go on read a question and then I know the question.  Sometimes it's confusing so I'll read it over again and think about what it is saying and then go back to my text and look at that for answers.

I:  OK

C:  When I was reading it I was wondering how the anteater worked and, what did it say? It had a sticky tongue.  It was a nostril at first—I thought it sucked up the ants with it.  I don't know.  But that's how it was in cartoons.  I didn't know—when I used to watch it.

 

I:  OK.  And what else did you do and think while you were reading?

C: I was wondering how they worked.  It was pretty interesting how about the butterfly that blended into trees. That was closer to the end.  Um…there was two butterflies that looked alike.  That was pretty sweet, but they were, they really weren't.  They had two different kinds of names and everything.

I:  When you were writing down all the things that you could remember, what were you thinking while you were doing that?

C:  Thinking what I could think—trying to remember what I had to remember.  Cause sometimes, see, it comes back to me, but I don't know how to write it down on paper sometimes.  It comes to me but, um, like I said, I don't know, sometimes I don't know how to write it down on paper, and sometimes I don't remember right after I read it.  It comes to me by the time the test comes.  Or something like that.

I:  What do you do to make it come to you?

C:  Just try to ... sometimes I pray to help um, try and remember myself, what happened.

I:   What happened, you mean in the book?

C:  Yeah.

I:  How do you do that?

C:  Well, I just, um...,say in my head sometimes, "Dear Lord, could you please help me with this test so I could

pass it and try and help me to remember what I read in the book and I'll try to remember, too.  In Jesus name,

Amen".

I.  OK, that's a strategy.  When I asked you the questions about Ann Arbor and the White Coyote, what were you thinking about while you were answering those?

C:  Well, I was, I don't like mosquitoes but I'm glad like everything, it just came to me, everything on earth has to do with something.  Like if the trees weren't here we wouldn't have this much oxygen, and if the mosquitoes weren't here, the frogs couldn't eat them and they would die.  And, um, I forgot what eats frogs but anyways, and it would go on like that and then eventually we would start dying cause we eat whatever, the frogs, see, wait a minute, that means... Oh forget it, but anyway, …That's weird.

I:  So when I was asking about Ann Arbor and the coyotes in Ann Arbor, that's the kind of thing you were thinking about?

C:  I was thinking how I wish everything could live.  Like everything would live forever. That's what I was thinking and now what would happen if that did happen.  And it would be colder on earth.

TABLE 1 Verbatim Responses of Students to Recall Task

Sharon's Response (as written by her)

I learned that adaptation is very important.

For example: a frog needs to eat insects.  The frog has a special tongue for that insect.  If the frog doesn't have that adaptation, it can not live on the insects.

I learned that Charles Darwin found the natural selting theory.  He found that all species do not look the same as their young ones.  The color of the young ones might be different from their parents.  Also that evolution takes place gradually.  This would be one of the reasons of the changes in the species.  Another reason would be the environmental changes.

For example: A butterfly might be a lighter color a long time back because the trees were light colored.  Now the butterfly became darker because the trees are darker.  The cause of the trees becoming darker is because of the environmental changes.  Thus there are two ways a specie might change over a period of time.

Mutation, I think is the changes occuring in the genes.  Mutations can help a specie do a certain activity.

Andrew's Response (as written by him)

Adaption—is the result of ___________  (left blank on sheet of paper)

Tadpoles and frogs are in the game species although they don't look the same.  There are two butterflies that look a like but aren't.

The anteater has a very sticky tongue and it is found in hard to reach areas.  It eats insects not only ants.

TABLE 2 Students' Response to Transfer Questions

Sharon's response (as transcribed from a tape recorder)

Ql:  What if Ann Arbor became very cold and had snow year round like the North Pole?  What might happen to the animals that live here now?

Mm, they might have to, mmm, in order, to survive here they might have to build some more homes, different kinds of homes that would keep them warm.  Or they might have to move, I don't know. (Interviewer probed for more information, but she said she didn't know.)

Q2:  What if a coyote that lives in the desert had a mutation that made his fur white?  What might happen to this coyote.

It wouldn't be, oh, Ok, since there as a lot of heat, it might not be able to protect itself.  Mm, it might, um, it might have some special, um, because when the fur is not white it might have some chemicals or stuff which might help the coyote get some food or meet his survival needs which he might not be able to get since he changed.  Maybe it's a different environment, I mean, maybe the coyote doesn't live in that kind of environment and is not used to the hot weather.  It's all I can think of. (Interviewer probed, but she couldn't offer anything else.)

Andrew's response (as transcribed from a tape recording)

Ql:  What if Ann Arbor became very cold and had snow year round like the North Pole?  What might happen to the animals that live here now?

We would be able to have more pet shops, be more animals I guess to help them.  Some animals can't live that long in cold weather.  They can't survive.  Bears will have to sleep all year round. They'd probably die. (I—What do you mean?) Since they have to sleep all year round and it, you know, you know how they, let's see, um, I don't know what it's called but they go to sleep in the winter I think.  Is that true?  I think they go to sleep in the winter and when it's winter, how are they going to survive?  If it is cold all year round? (I—Ok, you said there would be more pet shops, why was that?) Because, like, little, well not birds cause birds fly to where it's warm, so I'm talking about the animals, that live, like the animals that don't fly.  Probably bring in more animals instead of killing them.  So they can have a good life. (I—Do you mean they can live in the pet shops?) Or, I mean, yeah, yeah, or they could, like people could bring them home.  After they are trained and everything and get used to other people.  Since they are wild animals.

Q2:What if a coyote that lives in the desert had a mutation that made his fur white?  What might happen to this coyote?

Probably die, I'm not sure, I don't know that much about coyotes. (I—Tell me more about why you said, probably die.) The, like, I don't think coyotes get white fur, cause their fur is brown, I think—Sometimes, I'm not sure about this, but sometimes if their fur turns a different color, they're about to die.  Like if our fingers turned blue or stayed like that for awhile, we might die.