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Old 07-01-2011, 03:11 PM
 
Location: Cincinnati near
2,511 posts, read 3,366,086 times
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Originally Posted by lkb0714 View Post

But I also make it clear to all of my students the nature of models. You do not appear to do this. I explain to them that even the Wave Model is a VAST over simplification and is not how atoms actually "look" either. My students know that all of the models used along the way learning chemistry are fundamentally flawed and that includes the idea that electrons have "locations" (SINCE THEY DO NOT).
I have also struggled with teaching quantum chemistry to first year college students. The approach that I use is to tell them that we chemists are a pragmatic lot, and that we make models that give us results rather than any philosophical truth. The Schrodinger wave equation, paramaterized by quantum numbers, both explains and predicts the energies associated with electronic transitions as well as some other observed and quantified phenomena. This is a good enough reason to add it to our toolbox, even if assumptions that are made (such as wave particle duality) may require some suspension of disbelief for a first year student to swallow.

Models prior to Schrodinger I teach like history lessons, from Democritus to Thompson to Bohr, showing how each was more useful in both explaining and predicting new phenomena. In general chemistry I teach all of the models that the students will see on the MCAT or GRE, but in upper level spectroscopy classes it is almost all molecular orbital theory and spectroscopic term symbols. I would love to use SPARTAN or some other modeling program to explain molecular shapes andthe relationship of HOMO and LUMO to valence and conduction bands in crystals to general chem students but it really isn't feasible. It is funny because every year there is an upper level student that gets offended and says "You lied to us in general chemistry!".
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Old 07-01-2011, 03:18 PM
 
15,800 posts, read 13,239,318 times
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Originally Posted by Chemistry_Guy View Post
I have also struggled with teaching quantum chemistry to first year college students. The approach that I use is to tell them that we chemists are a pragmatic lot, and that we make models that give us results rather than any philosophical truth. The Schrodinger wave equation, paramaterized by quantum numbers, both explains and predicts the energies associated with electronic transitions as well as some other observed and quantified phenomena. This is a good enough reason to add it to our toolbox, even if assumptions that are made (such as wave particle duality) may require some suspension of disbelief for a first year student to swallow.

Models prior to Schrodinger I teach like history lessons, from Democritus to Thompson to Bohr, showing how each was more useful in both explaining and predicting new phenomena. In general chemistry I teach all of the models that the students will see on the MCAT or GRE, but in upper level spectroscopy classes it is almost all molecular orbital theory and spectroscopic term symbols. I would love to use SPARTAN or some other modeling program to explain molecular shapes andthe relationship of HOMO and LUMO to valence and conduction bands in crystals to general chem students but it really isn't feasible. It is funny because every year there is an upper level student that gets offended and says "You lied to us in general chemistry!".
Yup, the "lying" starts in elementary school and we teach them the "truth" at every new level. I've said it before but the majority of grad school has been learning the exceptions to the rules.

I think part of the problem maybe the investment of the student in the material. My students are all headed to science degrees so are not frustrated when I tell them "you must learn this model even though it isn't really correct" but I can see how some would be.

Maybe that is the best reason to have teachers holding higher degrees in their fields so they are aware of the "truths" beyond those taught in their classes.

Now that we are talking about "lying" in science class I will vent about my biggest pet peeve, the silly high school definitions of laws and theories. Even my textbook (a college freshman level one) makes it sound like theories can become laws with enough "proof". Ugh, makes me crazy. Ok I am done now. Sorry.
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Old 07-01-2011, 03:59 PM
 
920 posts, read 1,474,406 times
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Originally Posted by lkb0714 View Post
Yup, the "lying" starts in elementary school and we teach them the "truth" at every new level. I've said it before but the majority of grad school has been learning the exceptions to the rules.

I think part of the problem maybe the investment of the student in the material. My students are all headed to science degrees so are not frustrated when I tell them "you must learn this model even though it isn't really correct" but I can see how some would be.

Maybe that is the best reason to have teachers holding higher degrees in their fields so they are aware of the "truths" beyond those taught in their classes.

Now that we are talking about "lying" in science class I will vent about my biggest pet peeve, the silly high school definitions of laws and theories. Even my textbook (a college freshman level one) makes it sound like theories can become laws with enough "proof". Ugh, makes me crazy. Ok I am done now. Sorry.
My hs physics teacher use to tell us that the way physics was taught at unis was junk, that many times they said things that made no sense, and he tried to steer us toward engineering in order to for us to understand physics. After going through and studying the subject I realize now what he meant....
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Old 07-01-2011, 04:06 PM
 
Location: anywhere & everywhere
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Originally Posted by chielgirl View Post
Unless you're a teacher, or have been trained as one, what makes you think that getting a degree in education is easy?
It does take a lot to be a teacher. In many states, you have to pass various exams related to general liberal arts as well as in the area in which you are teaching. But the actual education classes are not difficult. Peruse a colelge that has its syllabi online and you will see what I mean.

I agree with the OP on some points. It used to be that people who were considered acaemically inclined went into teaching. That is no longer the case. When I was in college, I made money tutoring. I had a following of graduate students in teacher ed programs who came to me when they had to write papers. Mind you, these were simply papers about their field experiences in the classroom. I was but a lonely sophomore in college, and I had to teach them about thesis statements and transitioning from one idea to the next. Yet, they were already teaching and had made it through the bulk of their teacher ed programs without knowing how to write a simple 5-paragraph essay or even speak well enough to explain to me so I could help them with their papers.

I am not saying that teachers are dumb or that it is easy to be a teacher. Even the grad students who did not write well worked hard. I am simply saying that if you look at the teacher ed curriculum alone, you will see how many can come to think of teaching as something to fall back on and not the elite career that it should be.
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Old 07-01-2011, 05:02 PM
 
15,800 posts, read 13,239,318 times
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Originally Posted by itsasmallworld View Post
It does take a lot to be a teacher. In many states, you have to pass various exams related to general liberal arts as well as in the area in which you are teaching. But the actual education classes are not difficult. Peruse a colelge that has its syllabi online and you will see what I mean.

I agree with the OP on some points. It used to be that people who were considered acaemically inclined went into teaching. That is no longer the case. When I was in college, I made money tutoring. I had a following of graduate students in teacher ed programs who came to me when they had to write papers. Mind you, these were simply papers about their field experiences in the classroom. I was but a lonely sophomore in college, and I had to teach them about thesis statements and transitioning from one idea to the next. Yet, they were already teaching and had made it through the bulk of their teacher ed programs without knowing how to write a simple 5-paragraph essay or even speak well enough to explain to me so I could help them with their papers.

I am not saying that teachers are dumb or that it is easy to be a teacher. Even the grad students who did not write well worked hard. I am simply saying that if you look at the teacher ed curriculum alone, you will see how many can come to think of teaching as something to fall back on and not the elite career that it should be.
While I actually agree with most of your sentiments, and yes I am a teacher and YES all of the education classes I had to take were not difficult, but I do have to point out the flaw in your admittedly anecdotal experience. The only people who come to tutors are those who are struggling. Therefore you wouldn't have seen any (and presumably majority) of the would be teachers who were not struggling.
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Old 07-01-2011, 05:47 PM
 
1,428 posts, read 2,777,398 times
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Originally Posted by lkb0714 View Post
The Bohr model is also flat out wrong.

The problem is the only "correct" model is far outside the ability of most people to visualize especially high school students who do not understand quantum mechanics. It is not just about probability as Ivory is stating.

The reason we teach models at all is to simplify. All models should be taught with that clearly stated. If you tell a child that the solar system model is an oversimplification that is no different then teaching them the Bohr model which is also an over simplification.
Then choose the least wrong model that can be usefully explained.
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Old 07-01-2011, 05:49 PM
 
1,428 posts, read 2,777,398 times
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Originally Posted by lkb0714 View Post
Maybe that is the best reason to have teachers holding higher degrees in their fields so they are aware of the "truths" beyond those taught in their classes.
.
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Old 07-01-2011, 06:16 PM
 
Location: Whoville....
25,393 posts, read 29,785,394 times
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Originally Posted by lkb0714 View Post
You think the nesting dolls is a "correct" way to picture orbitals?

REALLY?

Based on the post above I seriously question your knowledge on the actual atom. The wave model needs to include FAR MORE than "probabilities" to predict anything close to correct behavior of atoms. Electrons ARE NEVER IN A SINGLE LOCATION.

You seem to think the models you are teaching are correct. I assume you teach VSPER but the reality is VSPER is incredibly crude and downright wrong in the majority of bonding situations. Be that as it may I still do not teach high school students MO (a more correct model) because it is outside their grasp based on their current understanding. Why? because VSPER is easier to understand.

But I also make it clear to all of my students the nature of models. You do not appear to do this. I explain to them that even the Wave Model is a VAST over simplification and is not how atoms actually "look" either. My students know that all of the models used along the way learning chemistry are fundamentally flawed and that includes the idea that electrons have "locations" (SINCE THEY DO NOT).

It is hypocritical bordering on disturbing that you think that mid-level model of understanding is "correct" and a model that is just even more simplified is "wrong". You do know that they are called "orbitals" because the was once considered the "correct" atomic model right?

You know what, maybe the higher degree thing is not a bad idea, especially in the field people teach since some do not seem particularly well versed in their own subject. I have had my mind changed to the necessity. Good job OP.
It's a simple way to show that higher energy levels are farther from the nucleus. And yes, I do explain to my students the nature of models. The problem is, they enter my class thinking that electrons orbit the nucleus like little planets around a sun and that idea sticks. I would rather see some kind of nesting orbital model used. At least that makes some sense when it comes to bonding. You can talk about overlap of orbitals with "orbitals" being some fuzzy undefined thing that will be defined later in chemistry.

I used the dolls with my daugher (then about 7) because I wanted to make it clear that the electrons could be anywhere in the orbital. I wanted to be sure she didn't subscribe to the solar system model. I oversimplified to say the electrons could be anywhere "on" the surface of the doll in question but it's a quick jump from there to a probability shape later on since the dolls have a shape.

I teach VSEPR and HO theory and I introduce MO theory. I explain to my students that, like the Lewis dot structures, VSEPR theory and HO theory are useful but they have their limitations. Unfortunately, my students come to me thinking that the solar system model of the atom is THE model of the atom and they've beleived this for years. I really wish they'd just stop teaching this. It's not something I can build upon. I have to unteach it to move on and even after telling my students it is wrong I end up with students who describe the atom as a little solar system.
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Old 07-01-2011, 06:18 PM
 
15,800 posts, read 13,239,318 times
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Originally Posted by Charles Wallace View Post
Then choose the least wrong model that can be usefully explained.
In elementary school, for typical students, that is the "solar system" model.
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Old 07-01-2011, 06:28 PM
 
Location: Whoville....
25,393 posts, read 29,785,394 times
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Originally Posted by Charles Wallace View Post
Then choose the least wrong model that can be usefully explained.
OR simplify the model in such a way that you can later BUILD upon it rather than having to explain it's wrong.

IMO, it, seriously, errodes the authority of teachers for me to have to tell students their previous teachers taught something wrong. Kids are not stupid. They want to know why someone wasted time teaching them something that was wrong. You can teach this in pieces. Atoms are made up of protons and neutrons at the center and surrounded by "clouds" that contain the electrons and leave it at that. Why does anyone have to add that they're orbiting the nucleus like little planets around a sun? I can add too and expand a concentric cloud model. I have to tell my students that the solar system model is just plain wrong.
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