Tag: astronomy

But did they learn anything?

The course transformations I work on through the Carl Wieman Science Education Initiative (CWSEI) in Physics and Astronomy at UBC are based on a 3-pillared approach:

  1. figure out what students should learn (by writing learning goals)
  2. teach those concepts with research-based instructional strategies
  3. assess if they learned 1. via 2.

Now that we’ve reached the end of the term, I’m working on Step 3. I’m mimicking the assessment described by Prather, Rudolf, Brissenden and Schlingman, “A national study assessing the teaching and learning of introductory astronomy. Part I. The effect of interactive instruction,” Am. J. Phys. 77(4), 320-330 (2009) [link to PDF].  They looked for a relationship between the normalized learning gain on a particular assessment tool, the Light and Spectroscopy Concept Inventory [PDF], and the fraction of class time spent on interactive, learner-centered activities. They collected data from 52 classes at 31 institutions across the U.S.

The result is not a clear, more interaction = higher learning gain, as one might naively expect.  It’s a bit more subtle:

Learning gain on the LSCI and Interactive Assessment Score, essentially the fraction of class time spent on interactive instruction. Each point represents one class with at least 25 students. (Prather et al, 2009) Our UBC result from the Sep-Dec 2010 term is shown in green.

The key finding is this: In order to get learning gains above 0.30 (which means that over the course of the term, the students learn 30% of the material they didn’t know coming in) — and 0.30 is not a bad target — classes must be at least 0.25 or 25% interactive.  In other words, if your class is less than 25% interactive, you are unlikely to get learning gains (yes, as measured by this particular tool) above 30%.

Notice it does not say that highly interactive classes guarantee learning — there are plenty of highly-interactive classes with low learning gain.

Back in September, I started recording how much time we spent on interactive instruction in our course, ASTR 311. Between think-pair-share clicker questions, Lecture-tutorial worksheets and other types of worksheets, we spent about 35% of total class time on interactive activities.

We ran the LSCI as a pre-test in early September, long before we’d talked about light and spectroscopy, and again as a post-test at the end of October, after the students had seen the material in class and in a 1-hour hand-on spectroscopy lab. The learning gain across 94 matched pairs of tests (that is, using the pre- and post-test scores only for students who wrote both tests) came out to 0.42. Together, these statistics put our class nicely in the upper end of the study. They certainly support the 0.30/25% result.

Cool.

Okay, so they learned something.  How come?

The next step is to compare student performance before and after this term’s course transformation. We don’t have LSCI data from previous years, but we do have old exams. On this term’s final exam,  we purposely re-used a number of questions from the pre-transformation exam. I just need to collect some data – which means re-marking last year’s final exam using this year’s marking scheme. Ugh. That’ s the subject of a future post…

Wasn't expecting Him in class

In the #astro101 class I’m working on, we just reached the “what is life” section. Great timing, considering the new @NASA astrobiology discovery of a bacteria that, unlike every other living creature, uses arsenic instead of phosphorus in its DNA.

We were going to have a PPT slide that listed 4 “generally agreed-upon” characteristics of life

Four "generally agreed-upon" characteristics of "life". Kind of a boring PPT slide for such an intersting topic, no?

<Yawn> I suggested to the course instructor we switch it into a #clicker question, to get the students to critically think about each characteristic and then compare them to what they think “life” means:

The same content posed as a clicker question to, er, lure the students into thinking about each characteristic.

I intentionally added the last choice “E) other ______” so students could add their own ideas. The instructor and I talked about it ahead of time, and agreed that if students chose E), we’d invite them to share their ideas with the class.

Fast forward to class. We pose the question, not as a think-pair-share sequence but just inviting them to discuss it with their neighbours. Then the students voted.

Students' votes for A, B, C, D, E.

Excellent – 4 others. Wonder what they are?

“What other characteristics should a life form have?”

Then the shocker. From the back of the room comes

“God!”

In hindsight, we should have expected that! But we weren’t prepared for it. Kudos to the instructor, though: without even a pause, she replied, “Well, we’re not going to add religion and philosophy to this science class. Okay, let’s see how these 4 characteristic apply…”

The student’s answer was a great one. It told us he’d thought about the question we posed and compared it to his own knowledge, experience and beliefs. Who could ask for anything more? Be warned, though: if you want to invite your students to bring their religion into your astronomy class, be prepared – you can’t just wing it. (I did that once. Big mistake. Made me look pretty – no, make that very – ignorant.) And if you’re not familiar with the spectrum of religious beliefs in your classroom, you might want to reconsider the conversation before you start it. Why not be up front about it with your students:

Whenever people talk about the origin of life, some will undoubtedly want to include their religious beliefs. In this class, though, we’re going to stick to the scientific aspects of the discussion, the aspects that can be predicted, observed, proved or disproved by the scientific method. Now, about those scientific characteristics of life…

Graph the graph on the graph

I was creating a worksheet for our #astro101 class about the expansion of the Universe. If the Universe is expanding at a uniform rate, it’s about 14 billion years old. If the expansion is accelerating (decelerating), a little logic tells us the Universe must be older (younger) than 14 billion years.

I wrote the worksheet as a ranking task (“Rank the 3 models by expansion rate 1 billion years ago” and so on) using the great collection at UNL as a template. There’s also a nice graph that helps summarize the current, past and future expansion of the 3 models. This is the graph for my analogy of 3 runners, Connie (who runs at a constant rate), Alice (who accelerates) and Deena (who decelerates) practicing for a 100-metre race. The Universe version is identical except “distance” is “size of the Universe” and “cross finish line” is “now”.)

Three runners cross the finish line at the same time and going the same speed. When did they start running?

I agonized (well, that’s a bit strong but you know what I mean) over getting the students to draw the 3 curves for the uniform, accelerating and decelerating Universes or getting them to identify and label the curves given in a diagram. Fortunately, we have nice set of learning goals for the course and one says, “You will be able to sketch different scenarios for the evolution of the size of the Universe, including when the Big Bang happened and the fate of the Universe.” That clearly told me to use “Sketch…” instead of “Label…”

Great. But is “sketch” the right verb? Soon, as a colleague and I started listing all the graphing nouns and verbs we use interchangeably, I realized once again that students most likely have many interpretations of these words. My “expert” interpretation is different than their “novice” interpretation of words like

  • sketch
  • draw
  • graph (noun and verb)
  • axes
  • diagram
  • figure
  • plot (noun and verb)
  • curve
  • function

It’s not inconceivable that a student could be asked to “graph the graph on the graph” or “plot the plot on the plot”. Ay caramba!

In the end, I asked the students first to “write labels Connie, Alice and Deena next to each runner’s curve in the graph” (the one above). I figured that showed them the critical feature of the story, that all three runners crossed the line at the same time and going the same speed. Then later I asked

This graph shows the size of the Universe at each time for the uniform expansion model. Sketch the curves for the accelerating and decelerating universes. Remember that all curves must go through the current Universe  and all curves must have the same slope at that point because the slope is the Hubble Constant. Label the curves accelerating and decelerating.

If the Universe expands at a uniform rate, right now is had its current size.

The students spent about 15 minutes on the worksheet. I’m happy to report that 103 of 115 (or 90%) of the students correctly chose C) older on this post-activity clicker question

If we discover the Universe is expanding at an accelerated rate, it means the Universe is

A) younger than 14 billion years
B) 14 billion years old
C) older than 14 billion years

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