COMPILATION: teach outdated models?
COMPILATION: teach outdated models?
(Editor's note: Read the related compilation entitled "AtomicModels-HowTeach04", of a listserv conversation that occurred at the same time, for a more complete understanding. Note Brant Hinrich's reference to Arnold Arons' book, "Development of Concepts of Physics", in that compilation.)
Date: Fri, 23 Apr 2004
From: "Vangilder, Clark"
Subject: Outdated Models?
A recent post to the list-serve stated, "I don't believe that other scientific disciplines such as biology teach outdated scientific models." Here are a few examples of "outdated models" in biology. [I wonder if this post will "stir the pot" of Darwinism?]
1. Heckel's Embryos: We've known for decades that Heckel's embryos were falsified...he just lied or got it wrong. There are significant differences between his pictures and reality. Also, he totally ignored the stages that precede the ones he illustrated, where things are even more different. Stephen J. Gould is at least one notable biologist who has recently called for the abandonment of Heckel's embryos in biology textbooks.
2. Finch beaks: ...still used to support the idea that natural selection will eventually give rise to a new species of finch. The Grant's (Peter & Mary, I think) published an article in Nature a few years ago that described how finch beak sizes oscillate in 5% increments with no net change per "environmental unit of pressure." [that unit is my paraphrase] There is no net change in the beak size over time. The National Academy of Sciences has published in its "Guidebook" that if there is one drought per decade for the next two centuries we might see a new finch. They cite the very article that rejects this notion. Even if the beak sizes changed, this does not do either of the two most important aspects of evolutionary change: (1) the organism is primed for an entirely new function, and (2) the body plan (soma) is changed. Big beaked finches and small beaked finches are still finches. Princeton biologist and mathematician, David Berlinski has criticized this as well, with much more eloquence and authority than I can muster at the present time.
3. Four Winged Fruit Fly: ...let's see, it can only live in the lab, it's second set of wings don't work...survival of the fittest? Mutation = new species? I'm confused.
4. Transitional forms: Recent discoveries at the Ching Cheng Institute for something I can't remember in the Yunnan province of China by a well known paleontologist whose name I can't speak or remember has found microscopic sponge embryos in pre-Cambrian layers of dirt. Since there are absolutely NO other fossils there, and since if soft-tissued sponge embryos were preserved, perhaps it is because all body plans (soma) arose from the Cambrian era and hence there are no transitional forms to find anywhere because that's the way it really happened? I'd like to know where they came from as well, but the evidence is contrary to the standard model...hmmm.
It appears to me that there is a materialistic philosophy that is driving the empiricism of biology. Biology tends to stay true to its philosophy in spite of the evidence. This may just be the mistake of assigning the potency of micro-evolution to macro-evolution...a regretful category error.
I do agree, however, that much of science education, biology or physics, could use some modernization.
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Date: Sat, 24 Apr 2004
From: Brenda Royce
The use of models is a way of representing a reality we need to work with in an accessible yet predictive manner. We use 'outdated' models when we use Newton's Laws since relativity has become the more comprehensive model, yet we continue very deliberately to teach models of reality based on 17-18th century ideas. In fact, students who cannot reason with these 'outdated' models don't seem to do so well with the physics in general. I think a better way to decide which model to use is to consider the 'accessible yet predictive' portion of the first sentence.
I am also a chemistry teacher, and I teach the development of the atomic model through the quantum model - enough of it to give students predictive power for the things they will be studying (compound formation, molecular shape...). They come to me having been taught (more or less) the electron orbit model (not orbitals). Is it wrong to teach middle schoolers this model because it is outdated? I don't think so because it is accessible to them at their stage of understanding and allows them basic predictive power for combining atoms. In high school, they can better grasp a basic quantum model of the atom and this prepares them for a more developed quantum model they will likely encounter in college chemistry. A truly 'outdated' model in my thinking is one that has been fully replaced (like phlogisten or the Ptolemaic 'solar' system) rather than amended because new details become available (Newton's laws or atomic theory).
I guess if I could summarize my ramblings, it is that we need to consider what students are needing to do with the models we teach and give them the tools best suited for the reasoning tasks we are asking them to do. If we choose to use a 'simpler' model (rather than 'outdated'), it is Ok (even advisable) to tell them this is not the final model.
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Date: Sun, 25 Apr 2004
From: Robert McDowell
I have a question from this discussion, which is, what is really meant by "outdated"? I realize that Newton's Laws are applicable only under certain conditions/assumptions. Yet, these same models are useful in helping to displace student misconceptions about the "real" world. I have not met too many high school students who are at a point in their thinking where they think in terms of subatomic reality. They can relate to a moving car and the forces acting on it much more readily than to the fourth dimension of relativity. I still have students who perceive constant force equals constant velocity; mass and weight are the same, etc. These misconceptions are extremely persistent, since most people in their childhood just keep adding new rules to their 'models' as they perceive new occurrences in the same type of physical phenomena.
Also, as I teach these 'outdated' models, I emphasize the limitations and restrictions inherent to the model. So these models are a foundation on which to start building the student's scientific thinking. I have also seen students really get involved in the class when we discuss the history of the model development, why it developed the way it did, and why the model changed or was eliminated. It really opens their eyes to how the scientific community works and why it does change the models as new evidence reveals shortcomings of the model.
Too often, we as a human race, tend to eliminate important historical information for cleaner and better methods, which actually cause us to stumble and fall (lose understanding that used to be considered common sense). So if a model works but only under restriction, does that make it outdated? Useless? Meaningless?
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Date: Mon, 26 Apr 2004
From: James Wittevrongel
I've been following this discussion with great interest. Surprisingly (or perhaps not) it has some valid application in my area of Middle School Mathematics.
Robert's comment: "Also, as I teach these 'outdated' models, I emphasize the limitations and restrictions inherent to the model. So these models are a foundation on which to start building the student's scientific thinking" strikes me as wise, even when teaching current "correct models", In my short 57 years I've seen a good many models go by the wayside. Discovery in physics is accelerating, not stabilizing. I have no doubt much of what we are teaching will need modification in the next decade.
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Date: Tue, 27 Apr 2004 08
From: Paul Gregg Swackhamer
One of the great benefits of modeling is that it requires us to determine what model we need to account for various phenomena. Then we can help students develop and use these models explicitly. While it is true that Newtonian models and the Bohr model of the hydrogen atom are no longer the most widely applicable models, they remain valid models for a range of important phenomena. Therefore, they are not only just OK, they are desirable to have students develop and use. In fact, ignoring more basic models in order to advance to the up-to-date models is often a major error.
One of the great mistakes that I see can be illustrated by the units about matter in typical middle school science texts. They typically proceed rapidly from the fact that matter consists of particles, to the fact that these particles are made of atoms, that atoms are made of nuclei and electrons, and that the nuclei consist of protons and neutrons. They often do not provide any particular deployments for these models. Therefore a detailed atomic model is practically useless for these students, and, it turns out, they do not "get it" anyway. For example, students have great difficulty describing solids, liquids, and gases in terms of even structureless particles, let alone in terms of atoms with orbitals and structured nuclei! For example, when a solid melts, some students believe that it is because the atoms themselves melt. Ask students what is between the atoms in a gas and they might just say "air is between the atoms!" The Chemical Concepts Inventory bears witness as well to the fact that even a structureless particle model for matter is generally not understood even by university students.
We asked about 350 physics students this year to sketch the best representation that they could for a helium atom. Only about 1/4 actually had two electrons traveling around two protons and two neutrons. A lot of them just drew a circle. Some had electrons in the nucleus. In short, just telling them about up-to-date models does no real good. Students have to develop and refine these models through using them.
It seems to me that dealing with structureless particles with long-range attraction and short-range repulsion is exactly what is needed (and what we actually think of ourselves) to account for solids, liquids, and gases. Of course, it is not the latest model. The latest models for matter would make us deal with protons and neutrons that have three valence quarks with underlying quark-gluon structure. No, what we need is a basic structureless particle model. That is how we account for the behavior of solids, liquids, and gases.
So the real question is not whether models are up-to-date, the question is: "What model do we need and actually use ourselves to account for the phenomena of interest?" These out-of-date models are actually of real value, because they have a useful range of validity. And even the most advanced physicist uses only the simplest model needed for phenomena in her everyday life.
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Date: Tue, 27 Apr 2004
From: Joseph Vanderway
Way to go Gregg! Gregg S. for president! I seem to vaguely remember Feynman saying something like if he could pass on a single idea to preserve our current understanding in all of science it would be that matter is made of particles with long range attraction and short range repulsion...
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Date: Wed, 12 May 2004
From: Jason B Lonon
Robert McDowell asked the question, "how does one define outdated?". I would like to further pose this question: "What is your definition of teaching?"
If teaching is the process of guiding one to construct knowledge about a system, which is the definition I subscribe to, then it becomes impossible to teach modern theories without first teaching older, replaced models.
If teaching is rote transmission, then yes, transmitting information about older models is pointless. Of course, research has shown that transmissionist teaching is pretty much pointless, so is it relevant?
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Date: Thu, 13 May 2004
From: Don Yost
Sorry for getting in late, but I was wondering what an "outdated" model was. A model is a representation and if it serves a purpose, it is a valid model. Even the earth-centered model is useful at times. I hear stuff like "the Bohr model is outdated because it's wrong." No, it's not wrong and it is a valid and useful model -- for certain applications. Chemists often propose a probability model as more "correct" than a Bohr model, but that is nonsense. As a model, the Bohr atom is a much easier way to understand orbit stability than the probability model. Yea, you may say, but it doesn't explain as many things as the probability model. So what, it models some concepts better, and the probability model is no more "correct;" it is simply more useful for some purposes. The probability model for the atom is still only a model reflecting some truths, but not all truths. In many ways it is flawed as the Bohr model, but who cares: models only reflect reality, they are not reality.
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