Dot Physics

I don’t know.

One the one hand, it would seem that teachers (and really I am talking about grade school level and maybe middle school) need to be good an managing students. What should a teacher have to help students? I think the first big question is “what is going to happen in the classroom?” Let me take two extremes:

Although I really don’t know the answer, I am going to lean towards – teachers need some content expertise.

Example 1

So, I had a workshop for middle school science teachers. This was some time ago. The basic idea was to help them increase their physical science content understanding. At the end of the workshop, we tried to help the teachers do new stuff in the classroom (that was related to the workshop content). I don’t think the workshop (only 3 weeks long) really made them content experts. What happened? It was quite interesting the questions the teachers brought up when trying to implement things similar to what we did in class.

Here is the deal. Since they were not experts (please don’t think I mean to say they were poor teachers) in that content, they weren’t sure what aspects of an activity could be modified. Any little thing that deviated from our description was put into question. Even brands of soap to be used and stuff like that. Oh, sure sometimes the brand of soap matters (I can’t even remember the activity – but I know it had soap), but in this case they just needed soap.

When you are not a content expert, you have no idea what aspects are important and which are not.

Example 2

One of the things I do in my physics for elementary education majors course is to give them the opportunity to try out an activity with some actual real-life kids. The goal is for them to take one of the activities and objectives that they worked on in class and help some kids.

In the class for the college students, they looked at force and motion. One of the key things was to see that when there is a force on an object, it changes speed. The primary way they build this idea is to use computers with motion detectors and carts on tracks. When you give a cart a “tap” with your hand, the speed of the cart changes. This is very easy to see on a speed-time graph. The college students also use some simulators that essentially do the same thing.

I have had several students try something similar by doing this:

“I will help students understand that a force makes things speed up. I will give them some soccer balls and let them kick them. When they do they will see that a force makes the balls speed up.”

This can still be a useful activity for the soon-to-be teacher. Hopefully, the college student will try this and talk to the kids. After the experiment I would suspect that the kids will have different ideas than what was intended. Why? When you kick a ball, it is really quick. The ball does indeed speed up, but how could you determine this without something else. Also, soccer balls kicked on grass will quickly slow down and stop. Students may use this to build on the idea that forces make things move. Without a force, it will stop.

If you are not a content expert in this area, it may be difficult to see where this could cause a problem – or to even know at the end that there is a problem.

Example 3

Take a look at Shawn’s blog – Think Thank Thunk. Look at the stuff he does in class. He is clearly a content expert. Yes, I know. When you look back at what he did, or if you look at Dan Meyer’s stuff – they both have this “let the students figure it out” attitude. Which I think is great. And looking at a particular activity, it seems like anyone can do it. But I think not. This is like saying anyone can walk the length of a 2 x 4 board. But, what if that 2 x 4 board is 40 feet above the ground?

walking a two by 4 across two buildings

– scared
– don’t know the answer
– don’t know what is important in an experiment


  1. #1 ijc
    April 13, 2010

    The word expert is a bit strong, but I do think teachers should have a genuine understanding of the things they are teaching. In your most specific example 2 I think any person who is familiar with the way basic physics discusses force and motion would reject that soccer kick as a not so good example.

    On the otherhand, merely surviving an ordinary college course in physics isn’t very good preparation for future teachers. Here is a great set of tutorials for training future teachers:

    although, these college tutorials are poor for traditional physics majors, they are great for future classroom teachers.

  2. #2 Jenny
    April 13, 2010

    As an elementary school teacher your question is one I’ve mulled over for some time. I don’t think it’s possible for me to be an expert on all the things I teach (as well as classroom management, students’ emotional issues, communication with families, and whatever else takes my time all day). That said, I’m not ready to let myself, or other teachers, off the hook that easily.

    Not being experts, or simply not knowing and/or thinking enough, about the things we teach means we inadvertently build misconceptions for our students. (Many of which you address here often.) Working on subtraction with first graders I’ve heard teachers say, “You have to start with the biggest number.” and “When you subtract you will always get a smaller number.” Now I know that first graders aren’t going to work with negative numbers and so these things are true for them, but these are certainly not rules about numbers.

    That said, I seem to agree with you that teachers need some expertise. Science, sadly, is the area in which I have the least content expertise and I’m certain I’ve set my students on the wrong path more than once.

  3. #3 speedwell
    April 13, 2010

    I am a corporate trainer in the IT department of a huge oilfield equipment company (in fact the first class for the launch of the new version of our software is today). My students are engineers and drafters. The software is briefly described as a product database, but it also helps manage product life cycles, track version changes, keep track of minor product details, link information to other information… the program is complicated and there’s quite a learning curve. I don’t pretend to know anything about mechanical engineering, and it’s my boss who’s the software engineer, not me.

    So how do I get away with training the students in just one or two days? Well, you can’t do this with children, I’m sure, but I admit right out loud in the beginning of class, “Hey, you guys know the products. It’s actually not my job to know the products. You know the products and you’re in charge of your product line’s data. I’m here to make sure you understand the difference between good data and bad data in our database. If I wanted you to be experts, I’d visit your facility for a month and we’d train every day. Instead, I want you to know enough to know when you’re making a mistake… to know how to ask informed questions… to know when something is going wrong in the software… to be able to do your job with the help of more experienced users in your group… to know what I’m talking about when I tell you how to fix something.”

    What this boils down to is that no, I’m expected to know very little about engineering. I’m expected to know vaguely about the products. I’m expected to be the resident expert on how to use the software, and I’m the second-line resource for user questions (part of my team handles the front-line user questions and passes the harder ones on to me). How to program and maintain the software and the servers is the job of my boss and most of the rest of my team.

    How does that apply to a teacher of children in a classroom? Well, I have face-to-face contact with users of the material. I have to be able to answer their questions meaningfully. I have to introduce new material. I develop learning content, multimedia, worksheets, reference material. I could theoretically equip someone in the Training department, who does not know or use the software, to run a training class if I develop all the content and carefully delineate the agenda. But the users would be unsatisfied and I wouldn’t be able to sleep at night.

    My job is not to simply present the material, it’s to make sure my students can actually do their jobs when they get back to their desks. From what I remember, and from what I understand, the job of a classroom teacher in an academic setting is… different from that. What would be different about your question, “Do teachers need to be content experts,” if teachers outside the corporation had the mindset that they were preparing students to do a task and to think about what they were doing, to ask the right questions, and to know when they’re on the wrong track?

  4. #4 Stephanie
    April 13, 2010

    I think you forget to take into consideration that good teachers need to know how to explain the content more than simply just know the content. An ability to effectively disseminate information will also help out with classroom management. If you can’t keep them interested, you can’t manage the students. And a teacher who can manage a class, but who doesn’t know class content will eventually frustrate and lose the respect of his or her students. I don’t personally think you need to be an expert, though a certain amount of knowledge is key. If you ask me, it’s not really a question of management vs. content, but a balance of the two. You can’t teach without classroom management, and you can’t teach information you don’t know.

  5. #5 Shawn Cornally
    April 13, 2010


    This is a great question. I had one of the most preeminent science ed. professors (Dr. Bob Yager) when I was in graduate school, and he gave an entire lecture on how teachers should not be experts. This rubbed my the wrong way, because he was essentially saying that my bachelor’s and master’s degrees were not just meaningless, but hindrances as well. His point was that an expert will not be able to avoid swooping in to solve a problem or connect knowledge for the students too early. Really, all he had to say was that, and we all got his point.

    It seems to me that your points are correct. It’s hard to teach what you don’t know, and even scary. However, if you have your governor tightened, and you’re committed to constructivism, the the combination of expert knowledge and inquiry methods can be staggeringly powerful. You just have to keep your mouth shut for longer that you’d like, and the kids will say some remarkably unexpected things.

    Thanks for the links, by the way!


  6. #6 Rhett Allain
    April 13, 2010


    Yes – I agree that one (even two) college physics courses would not make someone an expert (or even expert enough) in physics. Actually, most teachers will say that they learned the most physics by teaching (same here).

  7. #7 Rhett Allain
    April 13, 2010


    I also have pushed students off the path (by my incompetence) before. This doesn’t have to be a bad thing. Well, it is a bad thing if the goal is to have them ‘know’ some correct idea. It is not a bad thing if the goal is to help them think critically about what is wrong and what is not.

  8. #8 Rhett Allain
    April 13, 2010


    I think at one level, Yager was correct. Teachers shouldn’t _have_ to be experts. But, in practice, maybe they do.

    Love your blog, btw.

  9. #9 Coldbilly
    April 13, 2010

    Hmm… I agree with ijc. To further this discussion beyond my opinion and your opinion, you (someone?) needs to offer up a definition of “expert”. Second, I agree with Jenny. As long as “expert” is undefined, it is not possible for a person to be “expert” on all things they teach. (This is true at every educational level – although the scale slides, of course.)

    I also agree with Shawn. But I will take Shawn’s comments a bit further, perhaps. I say that teaching techniques – which is what I believe we try to do when we educate our teachers – will not and can not substitute for a lack of understanding of subject matter. And, if I were a teacher, I would be embarrassed to admit that there was ANY subject taught to a child between the ages of 4 to 16, say, of which I was not “sufficiently expert” (I exclude the “subjects” of grammar and spelling as being in that rhelm of mysterious “subjects” like astrology which are not meant to be understood.) It sometimes happens that applying techniques is all we can do when we don’t really understand. Yet I don’t want to believe this is America’s solution to 7th grade science education.

    As a parent, it seems to me that the real issue is not that middle school science teachers are often not subject matter experts about the subjects they teach, the real issue is that often they are not even interested in the subjects they teach. (If you come on here, by definition, you’re interested so hopefully no one reading this will take this as an insult.)

    As a parent, I don’t want teachers anywhere around my children who are not sufficiently interested in the subjects they teach to become “sufficiently expert” so that, at a minimum, they understand what kinds of questions to ask about simple, uncomplicated table-top experiments.

  10. #10 Scott
    April 13, 2010

    I am a middle school science teacher and I think an expert level is very important. Defining an expert is tough. I remember a quote that said, “Novices know the rules, experts know the exceptions.” I think this is key in teaching, particularly in science.

    To get to what I would call a somewhat expert level requires one to take upper level undergraduate classes. In the case of the biological sciences, you really don’t get much usable knowledge from G-Bio. You get the rules, but the intricacies and exceptions are not there. But, when you move on to higher level specific classes, you get to see what it is all about. You get to see what parts of G-Bio was really essential.

    As a teacher, that is important. We are given a list of standards to cover. One of mine literally says, “Knows the basic ideas related to biological evolution.” If the teacher only knows the “basic ideas”, then it is tough to create experiences for students to understand. If a teacher is an expert in evolution, then they know what the basic ideas are that will stand as a foundation for the further learning. And, as Rhett said in the post, then the teacher can modify. Every classroom has a ton of diversity. Some students will have the will, desire, and background knowledge to know more than the basic ideas. Others will need all sorts of different attempts and perspectives to see the concept. The expert can allow for that.

    I am a big fan of teachers creating their own curricula. The reason being is that teachers are then forced to figure out the important details and have the incentive to become experts. My favorite model for curriculum writing is Understanding by Design. If done right, the designer is forced to think about the really important, ENDURING understandings of the topic. In our trainings, we ask teachers to think about what they want students to know 40 years from now. You have to have a level of expertise to be able to answer that well.

    Sorry long post!

  11. #11 Alex
    April 13, 2010

    Your first example reminds me a lot of cooking. I can follow a recipe and cook something that tastes pretty good but that’s pretty much where my cooking skills end. If the recipe calls for dijon mustard and I only have deli mustard I don’t know enough to determine if this is an acceptable substitute. If a recipe calls for green onions and I don’t have any I don’t know if the dish will still taste good if I leave the green onions out. I haven’t tried giving this analogy to anyone but it might help illustrate the “expert” level we desire of instructors. I think it’s also a meaningful analogy for students to describe the difference between really understanding a concept and just knowing an algorithm for solving a problem.

  12. #12 Shawn Cornally
    April 13, 2010

    @Alex: I am powerless to resist a food analogy. I’ve spent a lot of time cooking professionally and at home, and you’re totally right. The extension here is that the only way to become substitution savvy or recipe-less is through massive amounts of experimentation and reflection.

    Your last line is the most important. After students have had a chance to experience knew knowledge with their hands, heads, and pens, then it becomes time to figure out at what depth that knowledge has taken hold. Same with cooking. Are chives a good substitute for scallions? The only way to know is to try it and log the results, which then might provide you more information about the entire onion family.

    This is why the teacher should be a well-governed expert. They can’t just start talking about the whole onion family, that’s like turning the fire hose on the kids, but you can “accidentally” leave the scallions at home some day and see what the kids do. You’d never know to do that without moderately advanced training.


  13. #13 Dan Meyer
    April 13, 2010

    I’ve used this particular XKCD cartoon every year for the last three years to realign my remedial classes towards the point of graphing coordinates:

    This particular image is so rich in mathematical content that even a content-area novice can find a handhold in the material. As I have grown in my understanding of information visualization and of coordinate geometry, the application has grown with me. One year we were just graphing five fruits we selected at random by students. The next year we were making an ordinal ranking of tastiness and then of easiness so we could see how much more informative it was to see both measures on the same plane.

    This is not to dispute the point that content-area expertise is valuable. It’s just to say that really well designed curriculum is accessible to all kinds of levels from novice to expert and in between.

  14. #14 Kaleberg
    April 14, 2010

    There are a lot of good reasons why teachers should have a good knowledge of what they are teaching. In Liping Ma’s book, Knowing and Teaching Elementary Mathematics, she points out that Chinese elementary school arithmetic teachers do a better job because they understand why things like carrying and borrowing work, and that lets them come up with alternate approaches and explanations as part of their teaching. American arithmetic teachers really didn’t understand why borrowing works, or why fractions work, so they had to teach the various by rote and couldn’t come up with ways of teaching children who couldn’t just “get it”.

    (It’s one of the few books with an acknowledgement to Chairman Mao for the Cultural Revolution that forced countless teachers out of the ivory tower and into the field. It reminded me of that book on the Trachtenberg method of speed mathematics which the author developed in a concentration camp to maintain his sanity.)

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