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Ellipses, eclipses and other confused concepts

By Murray Bourne, 04 Jun 2007

This is an interesting video, for students and teachers alike: A Private Universe (requires a login - the account is free).

The 20-minute video opens with Harvard graduates (and professors) who have really serious misconceptions about:

  • Why do we have seasons?
  • Why do we see different phases of the moon?

The focus then shifts to a local 9th grade classroom where students are asked the same questions. They also have wild explanations, but to be fair, they have had little formal instruction in these topics at this point. It is interesting to watch their science teacher squirm as her students clearly did not get the concepts that she had tried to teach.

I'm not surprised. Very few students (even at adult level) actually learn what they are taught. They only remember the parts that they can fit into their current belief system without too much re-alignment. Technically, this is what Piaget was talking about in his theory of Equilibration (source no longer available):

Equilibration encompasses assimilation (i.e., people transform incoming information so that it fits within their existing schemes or thought patterns) and accommodation (i.e, people adapt their schemes to include incoming information).

Back to the video. The shock displayed by the science teacher gave her a good lesson. Students arrive in class with a set of pre-conceived notions, experiences and beliefs. They are not empty buckets waiting to be filled with facts.

Another lesson was that even the strongest student (academically) was most comfortable when she was manipulating the models of earth, moon and sun with her hands. The concepts are difficult for her, and at a higher level than her concrete way of thinking.

I am constantly advocating that science and engineering should be taught in concrete ways wherever possible. Bring in the models. Lets students touch, feel, manipulate and solve problems using their hands. The mental concepts can - and will - come later.

One of the most common misconceptions held by students in the video was that the seasons are caused by varying distances of the earth from the sun. This thought most probably comes from textbooks which view the solar system obliquely, rather than from above.

solar system

While the earth's orbit is elliptical, it is very close to circular and certainly the distance does not change significantly.

I find it interesting when my own students confuse the words "ellipse" and "eclipse". Yes, the words are related, but such word confusion does not help with concept confusion.

Which science lessons do you remember best? Why were they memorable?

[The Private Universe video is 20 years old this year. I wonder how much the situation has changed.]

See the 1 Comment below.

One Comment on “Ellipses, eclipses and other confused concepts”

  1. Jose says:

    That's a worry. Are all Harvard graduates so confused, or was it just a chosen few Arts students who lost interest in science some time in the 3rd grade.

    I expect the situation has got worse, rather than better. Very few people even have any interest in the cosmos these days. Because of air pollution, light pollution and indoor lifestyles, no-one even sees or cares what is the phase of the moon, let alone what causes it.

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