Tag Archives: method

Rainbows and refraction

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Why is a rainbow always red on top and blue at the bottom?

We always talk about prisms and refraction and stuff, but be honest – would you be able to explain the order of colors in a rainbow without pausing and thinking first?

Screen shot 2014-07-13 at 3.34.19 PM

Rainbow. Picture taken in Laufenselden in 1996

As I said the other day, I am currently experimenting with screen casts. This is my very first attempt – I didn’t write a script so it is pretty chaotic, I have a cold (which you can hear from my voice), my handwriting sucks, the movie is, at 4 minutes, about twice as long as I wanted it to be – it is not perfect and I will certainly modify it before using it in teaching. But I would be very interested in your feedback so I can improve it!

As you noticed, this is a very textbook-y screen cast. I’ll present an alternative model for the same topic in my next post.

P.S.: As you might have noticed from the watermarks in the video, I have continued experimenting with screen cast programs and am currently using Doceri. And I am very happy with it!

Examinations via Skype.

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My experience with an examination via Skype.

In 2012, I taught two lectures via Skype at the University Centre of the Westfjords, while actually physically sitting in Norway. That experience is described in this post. When writing that post, I remembered that I also have experience in doing examinations via Skype. Except that experience was as a student, not as a teacher. In 2011, I defended a Master’s thesis at the University of Hamburg while, again, being physically located in Norway. How did that work out?

Defending a thesis via Skype is not that uncommon these days and actually a very easy, cheap and environmentally friendly way of defending when you no longer live in the place where you studied (or when you cannot travel there for other reasons). The way it worked in my case was that I had two opponents on the call, and since we were all to cheap for the upgrade, we could only hear each other and did not have a video connection. Which made it less stressful for me – when I am video-skyping, I tend to focus on my own video way too much, and thinking about how weird my hair looks or how I should sit in a specific position to block something behind me that would otherwise be visible. This tends to take away brain power from the topic I should be focussing on. Since I knew both their voices, there was also not an issue with knowing who was speaking at any given time (if you are ever on a call/skype with a group of people and there is even one person who doesn’t know everybody else really well: Please make sure to always announce who you are when you start speaking!).

I had to give a presentation, which I did by sending them the slides in advance and asking them to look at specific slides while I was talking about them. Thanks to my friend Nadine who let me borrow her apartment, I had a fast internet connection and privacy. What more do you need?

The only stressful time was waiting for them to call back after the exam when they were discussing my grade, but I guess that is a really stressful time no matter the setting.

So yes – examinations via Skype are actually a good option! No bad experiences here.

On drawing on the board by hand in real time

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Drawing by hand on the board in real time rather than projecting a finished schematic?

It is funny. During my undergrad, LCD projectors were just starting to arrive at the university. Many of the classes I attended during my first years used overhead projectors and hand-written slides, or sometimes printed slides if someone wanted to show really fancy things like figures from a paper. Occasionally people would draw or write on the slides during class, and every room that I have ever been taught in during that time did have several blackboards that were used quite frequently.

These days, however, things are differently. At my mom’s school, many classrooms don’t even have blackboards (or whiteboards) any more, but instead they have a fancy screen that they can show things on and draw on (with a limited number of colors, I think 3?). Many rooms at universities are similarly not equipped with boards any more, and most lectures that I have either seen or heard people talk about over the last couple of years exclusively use LCD projectors that people hook up to their personal laptops.

On the one hand, that is a great development – it is so much easier to show all kinds of different graphics and also to find and display information on the internet in real time. On the other hand, though, it has become much more difficult to talk students through graphics slowly enough that they can draw with you as you are talking and at the same time understand what they are drawing.

Sketch of the mechanisms causing westward intensification of subtropical gyres – here the “before” stage where the symmetrical gyre would spin up since the wind is inputting more vorticity that is being taken out by other mechanisms.

The other day, I was teaching about westward intensification in subtropical gyres. For that, I wanted to use the schematics above and below, showing how vorticity input from the wind is balanced by change in  vorticity through change in latitude as well as through friction with the boundary. I had that schematic in my powerpoint presentation, even broken down into small pieces that would be added sequentially, but at last minute decided to draw it on the whiteboard instead.

Sketch of the mechanisms causing westward intensification of subtropical gyres – here the “after” stage – the vorticity input by wind is balanced by energy lost through friction with the western boundary in an asymmetrical gyre. Voila -your western boundary current!

And I am convinced that that was a good decision. Firstly, drawing helped me mention every detail of the schematic, since I was talking about what I was drawing while drawing it. When just clicking through slides it happens much more easily that things get forgotten or skipped. Secondly, since I had to draw and talk at the same time, the figure only appeared slowly enough on the board that the students could follow every step and copy the drawing at the same time. And lastly, the students saw that it is actually possible to draw the whole schematic from memory, and not just by having learned it by heart, but by telling the story and drawing what I was talking about.

Does that mean that I will draw every schematic I use in class? Certainly not. But what it does mean is that I found it helpful to remember how useful it is to draw occasionally, especially to demonstrate how I want students to be able to talk about content: By constructing a picture from scratch, slowly building and adding on to it, until the whole theory is completed.

Q&A pairs

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Have students group in pairs, develop and answer questions.

It is really hard to come up with exam questions (or even just practice questions) that have the right level of difficulty so that students feel challenged, but confident that they will be able to solve the questions.

One way to develop those questions is to not actually develop them yourself, but have students develop them. So what I did in CMM31 was to ask students to group in pairs of two and develop questions that they thought would be fair exam questions. So they should be difficult enough that students have to think and employ a lot of what they learned during the course, but they should not be so difficult that they are impossible to answer.

You would think now that students would come up with really easy questions in order to trick you into giving an easy exam, wouldn’t you? There is a way to avoid this: After students have developed the questions in pairs (and made sure they know the correct answer), you can go around the room and have everybody share their question with the rest of the group (see? now having a difficult question makes you look smart!). The rest of the group answers the question, the person who asked the question has to say whether they are happy with the answers, or add to the answers if they feel like important aspects were not mentioned. Plus since there is an instructor in the room, he or she can always comment on the answers.

I usually say I give the students 10 minutes to come up with the questions (so 5 minutes each) and it then ends up being something like 6 or 7 minutes each. Since I’m sitting in the same room and listening in on the conversation, I can adapt the timing so it works best. Then it usually takes about 3 minutes to answer each of the questions so that everybody, including the instructor, is happy. So depending on the size of your group you might want to split the group into smaller groups so that exercise doesn’t take up too much time.

I find that using this Q&A pair method gives me a pretty good insight into what concepts students perceive as difficult, and how well the group as a whole can answer the questions. Since it is not the instructor asking the question, it seems to be much easier for students to throw in ideas (and I make sure that as the instructor I am not standing in front of the class, and when students start talking to me rather than the group, I point out who asked the question and that they should be talking to that person).

It does take up a lot of class time, but it is using class time for concepts that students feel are important and worth talking about.

Long-distance teaching.

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My experiences with giving a lecture via Skype.

As I mentioned in yesterday’s post, I taught two lectures at the University Centre of the Westfjords, Iceland, in 2012 while physically being in Norway. How did that work out?

Teaching via Skype is a great option for when travel is not in the cards, be it for environmental, economic or other reasons. But I can tell you – it is a lot more stressful than teaching in person because you miss out on all of the non-verbal clues that tell you whether or not students are following. But I would do it again any time!

Why did it work out well? I think there were several important factors. In no particular order:

1) I over-prepared. I tend to be over-prepared, but in this case I put a lot of time into preparations, and I even talked through both lectures with a friend to make sure they were structured in a way that was easy to understand.

2) I had all the important key words on the slides. I always try to make sure to have key words on my slides so students can write down any weird technical terms that I might use and forget to explain, but in this case I defined everything on the slides.

3) I had an ally physically present in the class room. I think this was probably the most important reason for why things worked out really well and why my stress levels didn’t go through the roof when we realized that the internet connection was too weak for a two-way video. When departing for a research cruise from Reykjavik and visiting someone at their marine research institute, I happened to walk into the lab of the person who was responsible for the course, Hrönn. Hrönn and I clicked immediately and so while I was on Skype talking to the class, I knew I could rely on her to make sure things went well on the other end and to give me all the crucial information that would otherwise not have been communicated – if students got bored, if students looked like they did not understand, if everybody had left the room and left me sitting there, talking, if the connection was so bad people couldn’t understand me, etc.. Even though in the end she did not have to do anything, it helped enormously to know that she was there and would let me know if things went wrong.

4) I introduced myself to the students. I put up a picture of myself, talked about my background, where I was living, why I was interested in oceanography, why I was skyping in to give the lecture. During the lecture, I mentioned examples of how the topic was relevant to my personal life and told stories of my own experiences. Teaching via Skype adds a lot of distance – I tried to still be visible as a person and connecting on a personal level as much as possible.

5) I sent the slides before the call. This might seem obvious, but it really helped to know that they had the slides in Isafjördur already and that in the worst case if the internet were to break down, I could just deliver my lecture via speakerphone.

6) The slides were numbered with clearly visible numbers in one corner. Again, it might seem obvious, but it was really helpful to be able to say “go to slide 16” rather than having to go through “go three slides back, see the diagram? No? Then try going back one more. Still no diagram? I’m talking about the slide with ….”.

7) I made sure I could see the students. Since the internet connection was very slow, we could unfortunately not have a two-way video call for the whole duration of the lecture. But what we did was this: They showed my slides via a projector (thankfully they were numbered!), my video stream was initially, until the connection became too slow, shown on a laptop that was moved to face the class, and I could see the class via that laptop’s webcam. I could only see shapes and not distinguish facial expressions, but when I asked them to nod or shake their head in response to a question, I could see them respond. Next time, I would maybe even try using the ABCD card method or some other way to get more direct feedback in a Skype lecture.

8) We had tested the technology before. We knew what part of the classroom was visible via the webcam so we could ask the students to sit there, we had tested connecting via Skype, we had the telephone numbers on hand as a backup and we “met up” in Skype a couple of minutes before the lecture was supposed to start. But maybe this should go under the “over-prepared” heading.

All in all – I can’t stress the importance of preparation enough, and if you are to teach via Skype: Make sure you have someone in that class that you know and trust to be your ear on the ground to let you know if things don’t go the way they are supposed to.

And have fun! In the evaluation of that course, people explicitly mentioned my lectures as a highlight of the course, and I got really positive feedback. So teaching via Skype might be a bit of a hassle, but it is definitely possible to teach well via Skype.

Melting ice cubes – what contexts to use this experiment in (post 4/4)

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What contexts can the “ice cubes melting in fresh water and in salt water” experiment be used in?

As you might have noticed, I really like the “ice cubes melting in fresh water and in salt water” experiment. Initially, I had only three posts planned on the topic (post 1 and 2 showing different variation of the experiment and post 3 discussing different didactical approaches to the experiment), but here we are again. Since I like this experiment so much – here are suggested contexts in which to use the experiment.

1) The scientific method.

No matter what introductory class you teach, at some point you will talk about the scientific method. And what is better than talking about the scientific method? Correct, having students experience the scientific method! This experiment is really well suited for that, because you can be fairly sure that most students will come up with a hypothesis that their experiment will not support.

2) Laboratory protocols.

For courses that include a laboratory component (like mine does), at some point you will have to talk about how to document your experiments. Again, since the hypothesis will typically not be supported by the results of the experiment, this is a great example on how important it is to write down the hypothesis and how you are planning on testing it, and then noting all the observations, not only the one that are along the lines of what you suspected. Also recording the little errors that occur along the way (“someone swapped the cups with the ice cubes, so we are not sure any more which one is which”) is very important, and if you have a class doing this experiment, you can be sure that at some point someone will make a mistake, not write it down and then be very confused afterwards. Great teaching and learning opportunity!

3) Different teaching methods.

If you are teaching about didactical models, this experiment is very well suited for this, too (see my post 3 on the topic and the Lawrence Hall of Science resource). Just have different people work on the experiment using the different methods and then discuss what and especially how people learned using those methods. The Lawrence Hall of Science resource mentions a fourth method (and I didn’t want to give the impression that I am recommending it, therefore I omitted it in my post 3) – the “read and answer” method, where students read about density, stratification and density-driven circulation and then answer questions like “what is density?” or “what is thermohaline circulation”. Again, not recommended for your oceanography class, but adding this option might be very relevant if you are teaching students or educators how to (not) teach.

4) Oceanography and climate

Yes, this is probably the main reason why you are doing this experiment in class. Now you can talk about salt in the ocean. About density-driven currents (and are there other things that drive currents apart from density differences?). About the importance of ocean currents, heat transport, the global overturning circulation, fresh water and many more.

Can you think of more contexts for this great experiment? Let me know! (Depending on your browser, you can comment on this post in the “leave a reply” box below or, if you don’t see that box, by clicking the speech bubble next to the title of the post.)

Introducing voting cards (post 3/3)

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How do you introduce voting cards as a new method in a way that minimizes student resistance?

As all new methods, voting cards (see post on the method here, and on what kind of questions to ask here) first seem scary. After all, students don’t know what will happen if they happen to chose the wrong answer. Will they be called out on it by the instructor? Will everybody point at them and laugh? And even if they chose the correct answer, will the instructor make them explain why they chose that answer?

Some of my students in a staged photo. They are showing their favorite color to demonstrate the method for you. Thanks for posing for me!

When I introduce voting cards to a new group of students, I make sure to talk through all issues before actually using the cards. It is important to reassure the students that wrong answers will not be pointed out publicly, for example. It helps to use a very simple question that does not have right or wrong answers (“Which of these four colors is your favorite? Show me the one you like best!”) for the very first vote, so students get to experience the process without there being anything at stake. While showing their favorite color, they see that they cannot actually see their neighbors’ choices without making it very obvious (at least not in the classical lecture theatre setting that we are in, but even in other settings it is difficult). Hence their peers cannot actually see their own choice, either, without again making it very obvious.

In the picture above, students are very happy to show their votes to everybody – after all, there is no wrong answer and I asked them to pose. But this is what it typically looks like after students have gotten used to the method. During the first classes, voting usually looks more like this: Very close to the chest, held with both hands, shielding it from the neighbors.

During the first classes, voting usually looks like pictured above: Very close to the chest, held with both hands, shielding it from the neighbors.

Still there is probably going to be some resistance about committing to one answer because, after all, the instructor will still see it. But in my experience this can be overcome when the reasons for choosing the method are made sufficiently clear – that it benefits them to commit to one answer, because making thought processes explicit helps their learning. That it helps me, because I get a better feel of whether everybody understood a concept or only just the two vocal students, and whether I need to go into more detail with a concept or not. That it is a great basis for discussions.

Photo of an actual vote. In fact of the first vote after I asked them to pose for a staged photo (the one shown above). This question was clearly too easy!

After a couple of classes, voting cards are not even needed any more (although it can’t hurt to hand them out – it feels like less pressure if you could fall back on holding something up rather than speaking in public); discussion starts without having to be initiated through a voting process and subsequent questions for clarification. Also if they chose to still vote, students get much more daring in the way they hold up the cards – they stop caring about whether their peers can see what they voted for. So all in all a great technique to engage students.

Melting ice cubes – one experiment, many ways (post 3/4)

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Different didactical settings in which the “ice cubes melting in fresh and salt water” experiment can be used.

In part 1 and 2 of this series, I showed two different ways of using the “ice cubes melting in fresh water and salt water” experiment in lectures. Today I want to back up a little bit and discuss reasons for choosing one over the other version in different contexts.

Depending on the purpose, there are several ways of framing this experiment. This is very nicely discussed in materials from the Lawrence Hall of Science (link here), too, even though my discussion is a little different from theirs.

1) A demonstration.

If you want to show this experiment rather than having students conduct it themselves, using colored ice cubes is the way to go (see experiment here). The dye focuses the observer’s attention on the melt water and makes it much easier to observe the experiment from a distance, on a screen or via a projector. Dying the ice cubes makes understanding much easier, but it also diminishes the feeling of exploration a lot – there is no mystery involved any more.

Demonstration of melting ice cubes. The melt water is clearly marked by the dye. This makes it a good demonstration, but diminishes the satisfying feeling of discovery by the observer, because the processes are clearly visible right away rather than having to be explored.

2) A structured activity.

Students are handed (non-colored) ice cubes, cups with salt water and fresh water and are asked to make a prediction about which of the ice cubes is going to melt faster. Students test their hypothesis, find the results of the experiment in support with it or not, and we discuss. This is how I usually use this experiment in class (see discussion here).

The advantage of using this approach is that students have clear instructions that they can easily follow. Depending on how observant the group is, instructions can be very detailed (“Start the stop watch when you put the ice cubes in the water. Write down the time when the first ice cube has melted completely, and which of the ice cubes it was. Write down the time when the second ice cube has melted completely. …”) or more open (“observe the ice cubes melting”).

3) A problem-solving exercise.

In this case, students are given the materials, but they are not told which of the cups contains fresh or salt water (and they are instructed not to taste). Now students are asked to design an experiment to figure out which cup contains what.

This is a very nice exercise and students learn a lot from designing the experiment themselves. However, this also takes a very long time, more than I can usually afford to spend on experiments in class. After all, I am doing at least one hands-on activity in each of the lectures, but am still covering the same content from the text book as previous lecturers who used their 180 minutes per week just lecturing. And I am considering completely flipping my class room, but I am not there yet.

4) An open-ended investigation.

In this case, students are handed the materials, knowing which cup contains fresh and salt water. But instead of being asked a specific question, they are told to use the materials to learn as much as they can about salt water, fresh water, temperature and density.

As with the problem-solving exercise, this is a very time-intensive undertaking that does not seem feasible in the framework we are operating in. Also it is hard to predict what kind of experiments the students will come up with, and if they will learn what you want them to learn. On the other hand, students typically learn much more because they are free to explore and not bound by a specific instruction from you.

How to pose questions for voting card concept tests (post 2/3)

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Different ways of posing questions for concept tests are being presented here

Concept tests using voting cards have been presented in this post. Here, I want to talk about different types of questions that one could imagine using for this method.

1) Classical multiple choice

In the classical multiple choice version, for each question four different answers are given, only one of which is correct. This is the tried and tested method that is often pretty boring.

An example slide for a question with one correct answer

However, even this kind of question can lead to good discussions, for example when it is introducing a new concept rather than just testing an old one. In this case, we had talked about different kinds of plate boundaries during the lecture, but not about the frame of reference in which the movement of plates is described. So what seemed to be a really confusing question at first was used to initiate a discussion that went into a lot more depth than either the textbook or the lecture, simply because students kept asking questions.

2) Several correct answers

A twist on the classical multiple choice is a question for which more than one correct answer are given without explicitly mentioning that fact in the question. In a way, this is tricking the students a bit, because they are used to there being only one correct answer. For that reason they are used to not even reading all the answers if they have come across one that they know is correct. Giving several correct answers is a good way of initiating a discussion in class if different people chose different answers and are sure that their answers are correct. Students who have already gained some experience with the method often have the confidence to speak up during the “voting” and say they think that more than one answer is correct.

3) No correct answer

This is a bit mean, I know. But again, the point of doing these concept tests is not that the students name one correct answer, but that they have thought about a concept enough to be able to answer questions about the topic correctly, and sometimes that includes having the confidence to say that all answers are wrong. And it seems to be very satisfying to students when they can argue that none of the answers that the instructor suggested were correct! Even better when they can propose a correct answer themselves.

4) Problems that aren’t well posed

This is my favorite type of question that usually leads to the best discussions. Not only do students have to figure out that the question isn’t well posed, but additionally we can now discuss which information is missing in order to answer the question. Then we can answer the questions for different sets of variables.

ABCD_lake

One example slide for a problem that isn’t well posed – each of the answers could be correct under certain conditions, but we do not have enough information to answer the question.

For example for the question in the figure above, each of the answers could be correct during certain times of the year. During summer, the temperature near the surface is likely to be higher than that near the bottom of the lake (A). During winter, the opposite is likely the case (B). During short times of the year it is even possible that the temperature of the lake is homogeneous (C). And, since the density maximum of fresh water occurs at 4degC, the bottom temperature of a lake is often, but not inevitably, 4degC (D). If students can discuss this, chances are pretty high that they have understood the density maximum in freshwater and its influence on the temperature stratification in lakes.

5) Answers that are correct but don’t match the question.

This is a tricky one. If the answers are correct in themselves but don’t match the question, it sometimes takes a lot of discussing until everybody agrees that it doesn’t matter how correct a statement is in itself; if it isn’t addressing the point in question, it is not a valid answer. This can now be used to find valid answers to the question, or valid questions to the provided answers, or both.

This is post no 2 in a series of 3. Post no 1 introduced the method to the readers of this blog, post no 3 is about how to introduce the methods to the students you are working with.

A, B, C or D?

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Voting cards. A low-tech concept test tool, enhancing student engagement and participation. (Post 1/3)

Voting cards are a tool that I learned about from Al Trujillo at the workshop “teaching oceanography” in San Francisco in 2013. Basically, voting cards are a low-tech clicker version: A sheet of paper is divided into four quarters, each quarter in a different color and marked with big letters A, B, C and D (pdf here). The sheet is folded such that only one quarter is visible at a time.

A question is posed and four answers are suggested. The students are now asked to vote by holding up the folded sheet close to their chest so that the instructor sees which of the answers they chose, whereas their peers don’t.

Voting cards are sheets of paper with four different colors for the four quarters, each marked with a big A, B, C or D.

This method is great because it forces each individual student to decide on an answer instead of just trying to be as invisible as possible and hope that the instructor will not address them individually. Considering different possible answers and deciding on which one seems most plausible is important step in the learning process. Even if a student chose a wrong answer, remembering the correct answer will be easier if they learn it in the context of having made a commitment to one answer which then turns out wrong, rather than having not considered the different options in enough detail to decide on one. “I thought A made sense because of X. But then we discussed it and it turns out that because of Y and Z, C is the correct answer” is so much more memorable than “I didn’t care and it turned out it was D”. Since the answers are only visible to the instructor and not to the other students, the barrier of voting is a lot lower because potentially embarrassing situations are being avoided. It is, however, also much harder to just observe the peers’ votes and then follow the majority vote.

In addition to helping students learn, this method is also beneficial to the instructor. The instructor sees the distribution of answers with one glance and rather than guessing how many students actually understand what I was talking about, I can now make an informed choice of the next step. Should I have students discuss with their neighbor to find an agreement and then ask the class to vote again? Elaborate more on the concept before asking students to discuss among themselves? Ask individual students to explain why they chose the answer they chose? Knowing how much students understood is very helpful in choosing the right method moving forward with your teaching. And even without staring directly at specific students, it is easy to observe from the corner of the eye whether students have trouble deciding for an answer or whether they make a quick decision and stick to it.

I have been using this method in this year’s GEOF130 lecture, and in a recent Continue. Stop. Start. feedback that I asked my students to fill in, every single student (who handed back the form, but that’s a topic for a different post) mentioned how the “A, B, C, D questions” or “quizzes” (which I both interpret as meaning the voting cards) help them learn and that I should definitely continue using them.

This post is number 1 of 3 on the topic of voting cards. Post no 2 will give examples of different types questions/answers that work well with this methods (for example always having only one correct answer might not be the most efficient strategy to foster discussions), and how to use them to maximize benefit for your teaching. Post no 3 will focus on introducing voting cards as a new method with least resistance by focussing on benefits to student learning and reassuring them on how the instructor will handle the information gained from seeing everybody vote.