Category: teaching

Motivation for pre-reading assignments

Image: chain by pratani on flicker (CC)

For the next 4 months, I’ll be working with an instructor in an 4th-year electromagnetism course. If you’ve taught or taken a course like this, let me just say, “Griffiths”. If you haven’t, this is the capstone course in E&M. It’s the big, final synthesis of all the electricity and magnetism and math and math and math the students have been accumulating for the previous 3-1/2 years. This is where it all comes together and the wonders of physics are, at last, revealed. It’s the course all the previous instructors have been talking about when they say, “Just learn it. Trust me, it will be really important in your future courses…” That’s the promise, anyway.

The instructor came to us (“us” being the Carl Wieman Science Education Initiative) because he wasn’t happy with the lecture-style he’s been using. Students are not engaging, if they even bother to come to class. He’s trying to use peer instruction with clickers but it’s not very successful. He wants to engage the students by giving them worksheets in class but he’s not sure how.

So much enthusiasm! So much potential! Yes, let’s totally transform this course, flipping it from instructor- to student-centered! Yes, and I purposely using the word “flipping” with all its baggage!

Hold on there, Buckaroo! One thing at a time. Changing everything at once rarely works. It takes time for the instructor to make the changes and learn how to incorporate each one into his or her teaching.

So, we’re tackling just a few things this term. The first is to create learning goals (or objectives) so we can figure out how to target our effort. In talking with the instructor, I learned there are very few new, mathematical techniques introduced in the course. Instead, the course is about selecting the right sequence of mathematical tools to distill fundamental physics out of the math describing E&M. That led us to this draft of one of the course-level, big-picture goals:

While you are expected to remember basic relationships from physics like F=dp/dt and λ=c/ν, you do not have to memorize complicated formulas we derive in class because a list of formulas will be given. Instead, you will be able to select the applicable formula from the list and know how to apply it to the task you’re working on.

The biggest change we’re making is the introducing effective pre-reading assignments. Oh sure, the instructor always said things like “Pre-reading for Lecture 1: Sections 12.1.1 – 12.1.3” but that’s not doing the trick. More and more of my colleagues are having success with detailed, targeted reading assignments. Rather than the “read the whole thing and learn it all” approach, we’re going to help the students learn (ha! Imagine that!):

Reading assignment (prior to L1 on Thu, Jan 10)
==================

Read Section 12.1.1. Be sure you can define an "inertial reference frame"
and state the 2 postulates of special relativity.

Review Section 12.1.2 (these concepts were covered in previous courses)
especially the Lorentz contraction (iii) and write out the missing steps
of algebra at the top of p. 490 that let Griffiths "conclude" Eqn (12.9).
Be sure you can explain why dimensions perpendicular to the velocity are
not contracted.

Read Section 12.1.3. Look carefully at Figure 12.16 so you're familiar
with the notation for inertial frames at rest (S) and inertial frames in
motion ( S with an overbar )

Now comes the hard part: getting the students to actually do it. It’ll take effort on their part so they should be rewarded for that effort. A reading quiz, probably in-class using clickers, worth marks could be that reward. (An online quiz we can use for just-in-time teaching might be even better but one thing at a time.) A straightforward quiz-for-marks promotes sharing answers (that is, cheating) and clicking for students not there (that is, cheating). I don’t want them to participate for that sole reason that they’ll be punished for not participating. I’d rather use a carrot than of a stick.

How do we present the pre-reading assignment as something the students WANT to do? Here’s a chain of reasoning, developed through conversations with my more-experienced colleagues. It’s addressed to the students, so “you” means “you, the student sitting there in class today. Yes, you.”

link 1: Efficient. You have a very busy schedule full of challenging courses. You want to use your E&M time efficiently.

link 2: Effective. We want the time you have allocated to E&M to be effective, a good return on your investment.

link 3: Learning. We recognize that many of the concepts will be learned when you do the homework. But rather than using class time to simply gather information for future learning, what if you could actually learn in class? Then you’d better follow along in class and you’d already be (partially, at least) prepared to tackle the homework.

link 4: Engagement. We’re going to create opportunities for you to learn in class through engaging, student-centered instructional strategies. But you need to be prepared to participate in those activities.

link 5: Preparation. To try to ensure everyone has neighbours prepared to collaborate and peer-instruct, we’re asking you to complete the pre-reading assignment. It will also save us from wasting valuable class time reviewing material that some (most?) of you already know.

link 6: Reward. This takes some effort so we’re going to reward that effort. If you do the readings as we suggest, the reading quiz questions we ask will be simple, a 5-mark gimme towards your final grade. Oh sure, you’ll be allowed to miss X of the quizzes and still get the 5%. Those marks are for getting into the habit of preparing for class, not a penalty for being sick or not being able to come class. The quizzes are also continuous feedback for you: if you’re not getting 80% or more on the reading quizzes, you’re not properly preparing for class. Which means you’re not link 5, 4, 3, 2, 1.

The big message should be, your effort in the pre-reading assignments will help you succeed in this course, not just with a higher grade but with better grasp of the concepts and fewer all-nighters struggling with homework.

Is it all just a house of cards? I don’t think so. And I’ll find out in the next few weeks.

Making memories stick. With Play-Doh.

My boss, Carl Wieman, likes to describe what we do as “looking for the pattern of how people learn science” (as he does in this video.) And the places to look are classroom studies, brain research and cognitive psychology. I certainly agree with the first place – that’s teachers and teaching. And research like this, that and this other thing about how the brain physically changes while you learn in very cool – that’s science. But cognitive psychology? I’ve been a science geek since, well, since before I can remember anything else, so I really haven’t been exposed to psychology and those other disciplines they teach on the “Arts” side of campus.

Carl says it’s important, though, and I trust him, so my colleagues and I read a cognitive psychology paper for our CWSEI Reading Group “What College Teachers Should Know About Memory: A Perspective From Cognitive Psychology” by Michelle D. Miller (College Teaching, 59, 3, 117, (2011)). Here’s a link, if you have access from where you’re clicking.

The paper is a nice summary of the models of memory. Short term, long term, working memory, ecological (or adaptive) memory. Here’s my interpretation. Every bit of information that’s stored in memory is accompanied by “cues”. Think “tags”, like the ones that accompany this blog post. When you see the cues, you recall the memory, just like finding blog posts by clicking on a tag. Without the tags, finding posts means paging through the archive. With a tag, you can zero in on the post. And the more tags on the post, the easier it is to find. Same with memories: the more cues linked the memory, the easier it will be to recall later.

Not all cues are created equal, though. As Miller puts it,

[u]nderstanding the role and importance of cues enables a richer and more accurate understanding of why people remember — and forget — what they do. (p.119)

Miller carefully crafted descriptions of the kinds of cues that trigger recall, so while I’m cutting them into a list and adding some bold, these are Miller’s words (p. 120):

Here are what I believe to be the cues that trigger us to “tag” information as being survival-relevant:

sensory impact, termed vividness: Concrete information that comes accompanied by sound, visual qualities, even tactile sensation tends to be more memorable than abstract information. Visual information is particularly salient to human beings, so that anything that can be visualized tends to be particularly memorable.

emotional impact is another cue that incoming information warrants long-term storage. Consider situations that relate to survival in a “natural” setting—a sudden danger, a new food source, encountering an enemy—and all would come accompanied with an emotional “charge.”

relevance to one’s own personal history is another indication that information will be useful in the future

structure and meaning—the ability to interpret information and put it into context—helps us distinguish useless background clutter from information that we need to keep

personal participation, as contrasted with passive exposure. This will come as no surprise to those familiar with the “active learning” trend. If we watch someone else do something, that activity may or may not be relevant to us, and it we will likely opt not to form a detailed memory of it. However, if we ourselves carry out the action, there is a greater likelihood that we will need to learn from and recall that experience later. We may also encode a richer set of cues when we are actively involved, which increases the likelihood of retrieving the information later.

Don’t you love it when you read an article that concisely and explicitly describes all those things you feel, in your gut, are important? It’s times like this that make me re-evaluate my naive and, frankly, prejudiced view of psychology, “C’mon, how can you possibly know how humans work?” “Oh, like that, ” he says, sheepishly. “Um, thanks. That’s cool!”

The week my colleagues and I read this paper, I was preparing the next activity for an introductory, general-education astronomy course I work on. This activity, like the others I’ve written and am sharing through the Astro Labs page on this blog, is a chance for “Astro 101” students to get some hands-on interaction with astronomy. Up next was the activity on black holes, especially spaghettification.

“Spaghettification”?

Talk about a made-up word, huh. Not by me, mind you. Chat with any astronomy instructor and you’ll find we all know exactly what it means because it’s the perfect word to describe what happens if you fall into a black hole.

<astronomy lesson>

A black hole with the mass of the Earth would only be about the size of a grape. Imagine it this way: if you could pack together and compress the entire Earth down to the size of a grape, the force of gravity would be so strong curvature of spacetime would be so high that not even light, traveling outwards as the speed of light, could escape.

That describes trying to get out a black hole. What about falling in? Let’s imagine you’re 2 metres tall and your lying on your back with your feet 2 metres from the black hole and your head 4 metres from the black hole. You can see it down there, between your feet, a little shiny grape a couple of metres away. It’s okay to think classically here, for a moment. Gravity is very strong but, being an inverse square law, it drops off quickly: your head is 2 times farther from the black hole than your feet so the force of gravity is only 1/4  as strong. What do you suppose happens when the black hole pulls 4 times harder on your feet? They get ripped off, that’s what. Your body gets stretched out as your feet accelerate towards the black hole, leaving your knees, hands, chest and head behind. This difference-in-forces is called a tidal force because these same kinds of forces occur in the Earth-Moon system where the Moon yanks on the water on Earth’s near-side and leaves the far-side water behind, giving us the tides. Newton worked that one out for us, more than 300 years ago.

The force of gravity between the Moon and the water on the near-side of the Earth is stronger than the force between the Moon and the more distance, far-side water. Earth's watery skin is deformed, giving us the tides. (Graphic: Peter Newbury CC)

Meanwhile, back at the black hole, the hapless astronaut is being pulled down a little funnel that ends up on the grape-sized black hole. Happy astronaut one second, long and skinny piece of spaghetti the next. Spaghettification, baby!

</astronomy lesson>

Ouch, that’s gotta hurt! LOL. Yeah. But how do we get Astro 101 students to remember it a month from now on their exam? Play-Doh, that’s how. Our activity progresses from setting up the phenomenon of tidal forces, to sample calculations demonstrating tidal forces are real, to recreating the spaghettification of a Play-Doh astronaut.

An astronaut falling into a black hole, before spaghettification...
...and after!

Here’s where the part about memory comes in. Students are potentially reluctant to play with Play-Doh. This is University. We’re not Children anymore. Teaching assistants and instructors are equally reluctant to ask students to play with Play-Doh. “Why,” they wonder, “should I?”

Because, I tell the teaching assistants who, if necessary, relay it to the students, it will help you remember. Playing with Play-Doh, stretching the poor astronaut’s legs, often pulling them right off his body, and squishing the Play-Doh into to a narrow strip, is tactile. And emotional – you just ripped his head off, dude! It gives relevance and a physical structure to those calculations. And it takes personal participation – oops, I just pulled his leg off!

Good in theory but how about in practice? The activity ran. The teaching assistants sold it. The students did it. All of them! Now we just have to see if they (1) learned anything and (2) can remember it. For (1), one of the questions they answer at the end of the activity is, “In your own words, describe what happens to the astronaut. Why do you think it’s called ‘spaghettification’?” Here’s one student’s answer, typical of many I thumbed through:

as the astronaut falls toward the black hole, feet first, its body stretches as it nears the black hole. the closer body parts (feet, then hands) stretch faster and fall faster than the head and body. It’s called spaghettification because the legs and hands stretch elongate like spaghetti.

Yep, I’ll take that. Would have been nice to see the word “tidal” in there but he did make the connection between closer and faster. For (2), we’ll be sure to put something on the final exam that tests this material. I’ll let you know in 4 weeks.

As my pop likes to say, “learn by doing.” Let’s update that to, “remember by doing.”

Thanks, Mr. Barsby

Today, October 5, is World Teachers’ Day 2011. My twitter stream is full of people sharing stories about their most memorable teachers. I can’t even finish reading the first sentence of any of these stories without thinking of my teacher, John Barsby. I don’t know if I ever properly thanked him for what he did for me. One blog post is far from enough but it’s a start.

Mr. Barsby, or JTB as we called him amongst ourselves, was my high school math teacher. I went to St. John’s Ravenscourt, a private school in Winnipeg, MB. (Thanks, Dad, by the way, for sending me there instead of River Heights and Kelvin.) There were about 80 kids in my Grade 8, enough for 3 classes. For math, they divided the kids into 2 “regular” classes with excellent teachers, I’m sure, and 1 “advanced” class for the kids who held promise in math. Or something. That was Mr. Barsby’s class. And I was in it.

This happened each year so I was lucky enough to have JTB every year, from Grade 8 until Grade 12. When I think back to high school, this class was my cohort, the group of close friends and familiar friends with whom I got through high school.

I don’t have time to describe all the things that happened in that classroom. One, I’ve got a meeting in 45 minutes and 2) high school was a long time ago and I’m turning into an old fogey, according to my daughter. But two things not just float to the surface of my memory, but jump from my memory whenever I think about JTB.

Ants by ceoln on flickr

He taught us about positive and negative numbers using red ants for positive, say, and black ants for negative. Whenever they meet, they eat each other. Red ants plus red ants means lots of red ants. Black and black: lots of black. But put red and black together and the total number of ants goes down. And what is good for red ants? Taking away some black ants: that double-negative is a good thing.

To this day, when I see one of my kid’s addition and subtraction exercises, in my mind I see what it looks like when you kick over an ant hill. Ants, red ones and black ones, scurrying about, adding and subtracting, until all the reds or blacks are gone and we’re left with just the sum.

That was how he taught us math, from positive and negative numbers right through to the 1st year University of Manitoba calculus course he somehow managed to teach us at our school. He used analogies and everyday experiences so we didn’t get bogged down in the mechanics of math. He taught us concepts.

[At this moment, I have to take a break cuz I’m gettin’ all teary-eyed. Happy tears, but still… Damn.]

Here’s what else I remember and it’s what I’m most thankful for. Even then, way back in Grade 8, I asked a lot of questions. Not stupid questions (“Mr. Baaaaarby, did you forget to square the 3 in the top line…?”) Well, maybe as many of those as the next kid, but the ones I remember were different. From what I know now, I was asking questions that made me more expert-like. Sense-making questions, which in math are often “push it to the limits and see if it still makes sense.” Like, when N gets really large, does the perimeter of an N-gon turn into the circumference of a circle? It does? Oh, cool.

I clearly remember some not-so-great moments when I’d toss out another of these. My classmates would groan, “Oh great, another question from Peter…” I could have stopped asking. I almost did. But I distinctly remember talking to my dad about not knowing what to do, and how he told me to tell my classmates, “to go suck eggs!” and keep asking questions. And I never, NEVER remember Mr. Barsbsy groaning or giving me the slightest hint of annoyance. In my head, I don’t remember any of his answers to questions but I still feel the comfort, the warmth (help me out here, I’m a science nerd with very little practice writing about feelings…) with which he welcomed and addressed my curiosity.  It’s the same feeling I’ve always had with my Dad (thanks again, Pop!).

I still ask questions. A lot of them. One of my role models is Simplicio from Galileo’s Two New Sciences. Simplicio asks a lot of questions of the wise and learned Salviati. Good questions. I like to think it’s almost like he knows what’s coming and asks just the right question at just the right time to help Salviati explain his discoveries. There’s a great line where Salviati says something akin to, “Ah, yes, excellent.  Let me just draw a diagram here in the dirt…” (I’ll update when I find it. Help me out?)

You see, I’m no longer afraid to ask those questions, the ones I suspect (or know) that other people have but are embarrassed to ask, or the ones I know (or suspect) will help the expert spit out a concept in a way the audience will get it. I’m quite happy to play the naive fool and put up with the occasional, “Oh no, here he goes again…” But I pick my questions carefully and thoughtfully. Just the right question at just the right time.

For the ability to ask think up those questions and the guts to ask them, thanks, JTB. You, too, Pop.

Navigation