Module 4: How the Students See It
C. Scientific Explanation
We often provide explanations, such as:
...why there is day and night; why the Moon goes through phases; why the stars shine; ....
Scientific explanations fall into 3 levels of intellectual development:
Let's look at children’s answers to the following problem.
A teacher asked her students to draw what the Moon looked like.
Some students drew it as shown on the left,
others drew it as shown in the middle,
and still others drew the Moon like the picture on the right.
Are these pictures all of the Moon?
If yes, then explain why the Moon has different shapes at different times.
Before we look at children's responses,
please write your own answers.
Consider responses by some school children.
How do their notions of a “scientific explanation” differ from your own?
Joe, 8 years old.
Interviewer: How can you explain these different shapes, Joe?
Joe: It divides itself in different shapes....
Interviewer: Does it ever put itself back together again?
Joe: In the daytime. In the nighttime it divides itself again.
Interviewer: Why is it that you can only see this part (pointing to crescent) or that part (pointing to half disk) at a time?
Joe: Cause it’s been divided up.
At what level of reasoning is Joe’s answer?
Joe’s explanation has reasoning at the egocentric level.
Egocentric explanations attribute motives and purposes to inanimate objects or assume all phenomena are produced by human actions for human purposes. Because the child has intention and purpose, he assumes everything else has these attributes as well. This mode of thinking is called “animism.”
Tina, 10 years old.
Tina: Something like its our planet or another planet covering half of it or the sun or something covering parts of it... Yeah, our planet.
Interviewer: How does our planet get up there in the sky?
Tina: Well, like I’m looking at it cause the shadow of the earth is on that part of it.
Interviewer: In this picture (pointing to half disk) where do you think the shadow of the earth is?
Tina: There is no moon like that.
Interviewer: You’ve never seen a moon like this?
Tina: There’s no such thing as that kind. It can only be curved, because the planet’s round and the moon’s round so the planet can’t be straight on one side to do that.
What level of reasoning is Tina’s answer?
Tina begins with the idea that something is covering up the moon and quickly proceeds to an explanation which involves the Earth’s shadow.
It is possible that she recalls learning about lunar eclipses and is confusing that explanation for phases of the moon.
When Tina realizes that her explanation doesn’t fit the straight shadow on one of the moon pictures, she rejects the picture as a fabrication!
Thus, her prior understanding of moon phases affects her ability to observe as well as explain what she sees.
Herbert, 13 years old.
Herbert: Because at different days, like a quarter moon, full moon, half moon, just changes its position.
Interviewer: How does changing its position change its shape?
Herbert: Cause, all right, if it spins around a kind of fog or mist can get on this part, and it will sort of look like a quarter moon....
Interviewer: How does one side get light and the other side get dark?
Herbert: Maybe cause reflections can’t see the dark side, the sun, but reflections can see the light side.
Interviewer: On here (pointing to the full moon) where is the dark side?
Herbert: In back.
Interviewer: In this picture (pointing to crescent) where do you think the sun is?
Herbert: Over in this direction. Like the sun is right here and it’s showing that part (indicating correct position of sun).
What level of reasoning is Herbert’s answer?
Herbert seems to have the right idea from the very beginning when he claims that the Moon “just changes its position.”
However, when asked to explain his ideas more fully he at first slips back to an explanation like that given by Derek, in which fog or mist covers the moon to cause the phases.
Then he switches back to the more advanced explanation involving reflected light coming from the Sun.
Herbert demonstrates that he can visualize the relationships by correctly explaining where the Sun must be in order to produce the lunar phase that we see. These more complex relationships are concrete level explanations.
Derek, 9 years old.
Derek: Because every month the moon, the clouds come over half of it. And then when the moon is full there’s no clouds around it. In a year then it goes back to normal.
Interviewer: Do the clouds stay that way all night? Or do they move around so you see it all different ways in one month?
Derek: No, it stays that way for a month.
What level of reasoning is Derek’s answer?
Derek’s explanation is more advanced than Joe’s since it involves only natural phenomena.
But like Joe, he accepts a simple association as an adequate explanation. Since many children have noticed clouds covering things like the Sun and Moon, it is not surprising that this explanation is common among children of this age.
Like Joe, Derek extends this idea to invent an explanation, but has little concern for the need to reconcile new observations. What is important for Joe and Derek is that their explanations make sense from their own points of view, indicative of egocentric reasoning.
In summary, students’ abilities to observe and explain what they see depends on their level of development and on their prior understanding of the phenomenon.
Young people can learn most readily about things that are tangible and directly accessible to their senses—visual, auditory, tactile, and kinesthetic. With experience, they grow in their ability to understand abstract concepts, manipulate symbols, reason logically, and generalize.... The difficulties many students have in grasping abstractions are often masked by their ability to remember and recite technical terms that they do not understand. As a result, teachers—from kindergarten through college—sometimes overestimate the ability of their students to handle abstractions, and they take the students’ use of the right words as evidence of understanding.
—Science for All Americans, American Association for the Advancement of Science, 1989, page 146.
At what level is the explainer is operating in this cartoon.
(egocentric, concrete, or formal)
© B.C. by Johnny Hart, reproduced with permission from Field Enterprises, Inc.
At what level is the Wizard on the right operating in the last frame?
© THE WIZARD OF ID by Johnny Hart and Brant Parker, reproduced with permission from Field Enterprises, Inc.