Galaxies and Cosmology -- First Experiences

(Posted by Dennis Ugolini, Associate Professor of Physics and Astronomy at Trinity University)

I am four weeks into the Coursera course "Galaxies and Cosmology," taught by Prof. George Djorgovski of the California Institute of Technology.  Fun fact:  I received my BS in Physics from Caltech in 1995, and was enrolled in Ay 21 (the basis for the online course) as a sophomore, twenty years ago with the same instructor.  Note that I said enrolled -- I had forgotten until recently that I dropped Ay 21 after a couple of weeks, having decided instead to take more optics and become a pure experimentalist.  So while the symmetry isn't perfect, at least the material is new to me, so I'm paying more attention.

The course is nine weeks long.  Each week's material is grouped thematically into two "chapters;" for example, the Week 1 chapters were History of Cosmology and Introduction to Relativity.  Lecture content is spread among 6-11 videos, each 8-12 minutes long, with an occasional multiple-choice question or two to reinforce concepts.  Most of the screen is filled with a PowerPoint slide (downloadable separately as a .pdf file), with Dr. Djorgovski shown at the upper left, seated and speaking to the camera, and the Caltech and course logo in the lower left.  The course website also recommends three textbooks and provides links to additional reading for each lecture. 

You get one point per video for viewing it, and up to ten points on a multiple-choice quiz each week.  Passing is 60%.  Watching every video and randomly guessing on each quiz gives you an expectation value right on 60%, while acing the quizzes but skipping the videos makes passing impossible.  So the course structure encourages you to (a) view the material and (b) just learn something along the way.

There is a discussion forum, as well as a teaching assistant who holds occasional "office hours," but I have not sat in on these yet.  At first the forums were dominated by people introducing themselves and forming study groups, and complaints about the course structure, particularly that you could only attempt each quiz once.  Oddly, most complaints came from people who scored 8/10 or close to it, but wanted to try again until they got it perfect.  Since then the forums have evolved towards questions on the material, with frequent answers from Dr. Djorgovski and the TA.  I was amused by the reaction to Dr. Djorgovski's note that the forums were not the place to discuss alternative theories for the origin of the universe, and that users who persisted in that would be banned.  Many people became frightened to ask questions, for fear that their misunderstandings would be construed as advancing alternative ideas.  Clearly they've never had to wade through a dozen "Einstein is Wrong!" posters at a conference.

Some thoughts after the first four weeks:

1.  The content is an abbreviated version of the Caltech course, but definitely not simplified.  There's a lot of calculus and some assumption of basic astronomy knowledge, and the pace is rapid.  But the quizzes cover only broad concepts with little math.  The idea again seems to be that they want you to learn something, and beyond that, you can go as deep as you'd like.

2.  I find that the concepts I remember the best are the ones addressed in the multiple-choice questions that interrupt each video.  No matter how simple the questions are, the fact that I had to stop and think, even for a moment, is reinforcement enough.

3.  I've toyed with creating video content in the past (for research-related outreach), but never followed through because I was worried about production values.  How much effort will it take to get fancy new graphics for each lecture?  Flying equations ala The Mechanical Universe?  Music?  This course has none of those things -- and I find I don't miss them like I thought I would.

4.  We only covered one chapter in week 4 because Dr. Djorgovski has the flu (feel better!).  Wait, the full course isn't already in the can?  He's making these on the fly as we go along?  That surprised me.

My interest in MOOC's is in providing a content bridge between high school and college, so that students with poor preparation (particularly in math) can catch up during the summer after senior year and arrive on campus ready to succeed in their intro classes.  I've seen too many students in physics and engineering doomed right out of the gate to a possible fifth year because they did not have the mathematical background to get through Mechanics.  So the most useful thing I've taken so far from this exercise are techniques for structuring a course that has just enough evaluation to make sure you have a pulse, while helping you get out of the course however much you put into it.