Is Explicit Vocabulary instruction Worth It?

I've been thinking about vocabulary a lot recently.  I've tried to teach vocabulary in a "robust" way in recent years (offering friendly definitions, using the words in context, playing fun games, etc.), but I haven't had much success.  Some kids knew the words already, some didn't; some studied, some didn't; most forgot the words by the end of the year.  I was dispirited.  Then, while following the common core debate, I noticed that in a recent letter in Education Week Linda Diamond defended the National Reading Panel Report and its emphasis on skills, "explicit instruction," and vocabulary instruction ("Common-core standards in reading not 'flawed,'" March 28). I was most interested in the question of vocabulary instruction, and I decided to try to figure out who was right, the Common Core Standards, the National Reading Panel, and the "What Works" Clearinghouse, or those who argue that explicit vocabulary instruction is probably less valuable than other activities, like reading itself.

My first step was to look up the government's "What Works" publication on adolescent literacy (http://ies.ed.gov/ncee/wwc/practiceguide.aspx?sid=8).  I found that this apparently authoritative, evidence-based publication said there was "strong" empirical evidence for explicit vocabulary instruction. When I followed up on their evidence, however, I was surprised to find that there was almost nothing there--and that some of what their strongest evidence seemed rather to question the value of explicit vocabulary instruction.

The strongest evidence cited by the What Works report seemed to be in the following passage: "Children often learn new words from context. However, according to a meta-analysis of the literature, the probability that they will learn new words while reading is relatively low--about 15 percent. Therefore, although incidental learning helps students develop their vocabulary, additional explicit instructional support needs to be provided as part of the curriculum to ensure that all students acquire the necessary print vocabulary for academic success.

This sounded interesting, but a little obscure. If the probability of learning new words while reading is "relatively low--about 15 percent," what exactly does that mean? 15 percent of what? Does that mean that 15 percent of my students learn NO words at all in the course of their reading? That would be terrible. Or does it mean that for any occurrence of a word they don't know, there is a 15 percent chance of their learning it? That doesn't sound so bad.

Curious, I followed the citation to a 1999 paper by a couple of researchers in Amsterdam, researchers who wrote in perfect English, of course. (An aside: how did they acquire their excellent English vocabulary? Not, I imagine, from much explicit instruction in vocabulary, but I could be wrong). These Dutch academics, Swanborn and De Glopper, had reviewed a number of studies of vocabulary acquisition from what they charmingly called "natural reading." They noted that some uncertainties remained, because there seemed to be great variability among students in how many words could be learned incidentally, and it was unclear also how many unknown words students encountered in their "natural reading," but the researchers concluded on a positive note: "What we do know, however, from our meta-analysis, is that students have a fair chance of learning unknown words from reading. Natural reading has the potential to make a contribution to vocabulary growth." This is, strikingly, at odds with the way the government publication interpreted their article. So I decided to look more closely, at the 15 percent that the What Works article had claimed was too low a number.

According to Swanborn and de Glopper, students encounter unknown words at a rate of at least one percent. That is, in a thousand words of text, ten of them will be unknown to a student who is reading a book that's comfortable for him to read. Of those unknown words, 15 percent will be learned without any conscious effort. The What Works authors deemed this too low a number. But how many words would a student learn at this rate? Say a student read ten pages a day, hardly impossible, and say each page had three hundred words, also a low estimate. Then in a week the student would have read 7x10x300 words, or 21,000 words. Of those words, at least one percent, or 210, would be unknown. Of those 210 unknown words, the student might be expected to learn 15 percent, or 31 words. So, according to the meta-analysis that the What Works authors cited to show the inadequacy of natural reading as a way of improving one's vocabulary, students who are reading at the relatively slow pace of 70 pages a week could be expected to learn 31 new words a week. At my school, we have had a big push in recent years to teach more vocabulary, and many teachers are spending as much as 10 or 15 percent of their class time to explicit vocabulary instruction. But even with this extraordinary expenditure of time and energy, no teacher is teaching her students more than 10 words a week, at the most, and few students are actually learning all ten of those words. With the hour a week that we are spending on vocab, our students could be reading another thirty pages, thereby learning another 13 words, and also accruing all the other benefits that reading brings.

It seems that having a 15% chance of learning new words is far from "too low"; instead, it is wonderful and promising. So the main evidence cited by the What Works authors does not support their argument that explicit vocabulary instruction is needed.

Natural reading may work to improve vocabulary.  But what about explicit vocabulary instruction?  Maybe research shows that explicit instruction is very effective--even more effective than natural reading, despite my own poor results.  So I looked at some of the research the report cited and I looked at some papers I found elsewhere, and NOWHERE could I find clear empirical evidence that explicit instruction in vocabulary would lead to more word acquisition than just plain reading, nor that the word acquisition that was achieved in any of the studies had actually increased comprehension.  As Baumann et al. say in their 2003 paper, "causality regarding vocabulary-to-comprehension relationships [...] remain [sic] murky."

This is typical of my experience with educational research.  The claims people make about what is supported by the data are often strikingly at odds with what the data actually support.  There is no doubt that good readers usually have good vocabularies, and there is no doubt that they acquired their good vocabularies somehow, but it is very far from clear how they did, and it is very far from clear what teachers can do to help.  In the absence of much clearer evidence that explicit instruction is significantly better than just reading, I think we should mostly stick with just reading.  That said, I am still going to do some vocabulary stuff in my classes next year.

This year, after I had my students learn vocabulary words drawn from the books we read as a class, they didn't make much progress.  Next year I am going to have them pay attention to words in the books they read on their own and make their own vocab tests from those words.  I also hope to be very intentional about using a lot of higher-order words in class myself.  A few weeks ago I used the word "behoove" a few times, and many of my weakest students loved it.  I'm skeptical about whole-class word lists, but I hope that modeling and encouraging word-love (and upping the reading volume) can make a difference.  We'll see.