Depth vs Breadth

The school year is approaching, and teachers around the nation are trying not to think too much about tweaking our courses for the next go-round.  Most of us have been blowing it off for months and we really have to give it some thought here in early August.  Part of my current focus is inspired by an article printed in the Washington Post this past February.  Jay Matthews wrote on the age old educators’ debate of breadth vs depth ^[1]:

The debate goes like this: Should they focus on a few topics so students have time to absorb and comprehend the inner workings of the subject? Or should they cover every topic so students get a sense of the whole and can later pursue those parts that interest them most?

The truth, of course, is that students need both. Teachers try to mix the two in ways that make sense to them and their students. But a surprising study — certain to be a hot topic in teacher lounges and education schools — is providing new data that suggest educators should spend much more time on a few issues and let some topics slide.

One of the (probably) unintended side effects to standardized testing is that teachers get together to parse the numbers and figure out what they can afford to skip over in our subjects. Standardized tests become predictable to some degree, enough that teachers can figure out which chapters are valued and which ones are not. In fact, that’s the whole point—make sure that every teacher knows what chapters are considered the most important. Make sure they know to cover those topics well.

I don’t think the people who create the standards expected teachers to completely skip those topics that aren’t emphasized on the test, but that’s what happens. The fact is that if you can get your students to score well on the couple of topics that are most heavily assessed, then they’ll pass the standardized test–especially when the tests are graded on a sliding scale ^[2]. Whether they meant to do it or not, they’re generating an atmosphere that promotes depth over breadth.

As Matthews notes in his article, the College Board’s Advanced Placement program is looking to embrace greater course depth at the expense of breadth. It may be more of a trend in high schools, and as a high school teacher I am cautiously optimistic. (I think it is arguably less appropriate for younger and younger students.) We must realize that it is precisely in these deeper waters that we run into the sink-or-swim situation. It benefits and stimulates our best students, but our worst students need another option… or else, we will need to accept that some students simply will fail.

Matthews expresses some concern about the dangers of choosing depth over breadth:

Some educators, pundits, parents and students will object, I suspect, to sidelining their favorite subjects and spending more time on what they consider trivial or dangerous topics. Some will fret over the possibility that teachers might abandon breadth altogether and wallow in their specialties.

But I think he’s missing the point. What if my specialty is nuclear physics, which is only 10% of the AP test ^[3]? How can I justify spending extra time on nuclear physics? Realistically, I could only get away with it if the students are able to pass the test, which means I still have to go into some depth on Newtonian Mechanics and at least one other topic. While the standardized tests do encourage some depth at the expense of breadth, they do so in specific areas, and not in whatever chapter the teacher chooses.

In fact, take a look at what Matthews says is skipped over:

The topics most neglected were history of biology, biochemistry and history of physics. Also on the lower end of the attention scale were evolution, nuclear reactions and relativity.

This gives me an idea. I think I’ll assign my students some history projects. I tried this years ago, and I didn’t like how it turned out. After all, I teach physics and not history. But I find that I can’t convey why certain things are important unless I get into the timelines involved. For example, when did Christiaan Huygens live?  There was a time when I had been under the impression he was a contemporary of Ben Franklin.  A lot of things suddenly made sense when I found out where he fits into things (he predates Franklin… and even Newton).

It seems to me that depth can be covered in class.  Breadth can be assigned.