What I have learned about teaching large classes (or) "Hard-Knocks Lessons from Mistakes Made"

Some history:

Oceanography is an extremely challenging class for the instructor. It is a large, general education lecture class with 200 to 300 students each quarter. It draws from a very wide student population, most of whom are non-science majors fulfilling a "quantitative science" requirement.Teaching duties are shared between the geology dept. faculty. I began in the usual lecture mode, with transparencies, trying to cover as much material as possible, a mid-term and final exam using multiple choice tests, and labs created and managed by teaching assistants.

My ideas and interpretations are based on discussions with students and TA's, and my own personal interpretation of student feedback that is given each time the course is taught. Normally, because of the wide range of student abilities, some will hate the professor and some will love him/her. However, themes can be extracted.

First try, multi-media lectures:

My first attempt at improving the course consisted of the creation of multi-media lectures which use clear, colorful graphics, animations, mixed with the usual videos and other material. This was a dismal failure, especially considering the work I put into it. The main lesson that I learned was:

1) Students are very concerned with knowing what they need to know to pass the course. The use of pretty graphics does not mean they are engaged in the material.

The introduction of multi-media into the lectures, made it hard to take notes, made it easy to go too fast, and made them very uneasy about how much content in the beautiful graphics they had to know. I compensated for this by creating books of figures, available in the bookstore. After I had "milked" this for all I could, student reaction remained mixed and "ho hum". The lecture format was not working. Students were not engaged. I'm not a gifted orator. The most successful of the faculty, in terms of student ratings, was an extremely funny character with good jokes, who used lecture demonstrations a lot and reduced the course content. I believe that he was successful because students felt they could master the material, the content was well-defined, and the lectures were entertaining. Most of us would agree that these are some of the basic ingredients of good teaching.

Second try, improved labs using computer available media and data:

This approach has been very successful. The first half of the quarter concentrates on a technical paper that counts for 30% of the students' grade. Students must access real earth data to support the theory of plate tectonics. I created the "Our Dynamic Planet" CD-ROM for this purpose. In addition, students enter their homework answers into the computer for automatic grading, review lecture graphics, and access other relevant course information. The creation of the mid-term paper is prefaced by a one page paper assignment, where they get a (harshly graded) try on a small scale. The creation of a technical paper is a challenging exercise for most students, who have never been asked to back up and argument with evidence. In addition, the real earth does not fit the cartoons in the textbook, so provides a more realistic and dynamic resource for them.

Some noticeable effect on students are:

The second half of the course is more like the standard lecture version. Lab exercises are supported by the lecture, but the rich data sources are not available. The contrast in student engagement and understanding of the material is obvious.

Click here for a description of the "Our Dynamic Planet" CD-ROM and "Class Master" course management software.

I help make the lecture more engaging by:

Covering less content:

The textbook covers so much material that it cannot possibly be absorbed in a single quarter. In addition, it requires great effort at the lowest cognitive level, which is memorization in preparation for regurgitating facts. Students know that they will forget much of what they have memorized and feel it is an "exercise" they must engage in to pass the course. Do we want students to see science as the memorization of science facts?
 
Now, I concentrate on the most important concepts for each topic that I cover. Even then, the minute papers demonstrate less understanding than I would hope for. However, covering less content, and the focus on the few important principles allows me to expose students to the same material more than once through review and the "Question of the Day" (see below).

Question of the Day:

Here students are handed a sheet of paper with a basic "big picture" question about the material. They use the first 5 minutes of class to enter their answers. They are allowed to use the book. They put a bar code label (the "Our Dynamic Planet" software supports bar code label creation) on their paper, and hand it in. It is scanned in and recorded in the students' records. Students get 10% of their grade for these activities, and it keeps attendance high. The answers are not graded, just checked off. Empty papers are discarded.
 

Minute papers at end of lecture:

Here students, in one or two minutes, answer: 1) what was the most important point or concept in today's lecture, and 2) what is the most outstanding question on your mind about today's lecture (or in general). This gives me feedback, on a regular basis, about what is going on in the class. It only takes a few minutes to scan enough papers to extract common themes. Students feel they are being listened to.

Lecture Demonstrations:

These can be difficult because of the logistics, so I use them sparingly. An easy one to do is to bring in a clear bowl, a can of diet Coke, and a can of regular Coke. Fill the bowl with water. Diet Coke floats, but regular Coke sinks. It's the sugar dissolved (about 8 tspns) in regular Coke that makes it denser. This initiates a nice class discussion on buoyancy and the idea that dissolved salts in water can make it denser, so it sinks. You can also pop the can and talk about dissolved CO2 in the liquid, and how a warm Coke spews more fizzy, because it can hold less CO2.
 
One I'm working on is Coriolis Effect. We have a rotating table in the lecture hall, that changes the room from a sink and bench at front to an empty space. The rotating table should show the Coriolis effect when a ball is rolled to the center (or center out) as the table rotates. I tried it, but it needs a precise ball launcher to see the effect. I'll let you know how this works in the future.
 
Do you have any lecture demonstrations that require a minimum of equipment? If you do, email me here, and I'll add it to this page.
 
Email ideas to W. Prothero
 

For now, this is all I can think of. If you want me to add your pet ideas, email me. I'll add 'em.

 

Bill Prothero

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