At the preschool at the University of Illinois at Urbana-Champaign that Engelmann ran with the education researcher Carl Bereiter starting in 1964, phonics-based direct instruction helped even 4-year-old kids understand sounds, syllables, and rhyming, so that they entered kindergarten reading as proficiently as 8-year-olds. Nine other sites across the country had comparable results. Direct instruction has boosted student performance in a similar fashion since in Houston in the 1970s, and in Baltimore and Milwaukee in the late 1990s to early 2000s.

In 2001, students in the mostly black Richmond, Virginia, district were scoring abysmally in reading—just less than 40 percent of third-grade students passed the state reading test. Four years later, after the district switched to the direct-instruction method, 74 percent of third graders passed it. By contrast, in 2005 over in wealthy Fairfax County, where teachers scorned the phonics-based-reading instruction method (dismissing it as impersonal “drill and kill” is common), only 59 percent of the county’s black third graders taking that test passed it, despite plush school funding.

One survey found that only 15 percent of classes for elementary-school instructors offer lessons in how to teach direct instruction. Many specialists insist that kids learn to read English better using the whole-word method. The idea is that English spelling is so irregular that it’s inefficient to try to teach kids to link how letters sound to how words are written.

Among education specialists, a school of thought has grown up around the idea, espoused by the psycholinguists Ken Goodman and Frank Smith, that people don’t mentally associate letters with sounds—that real reading is a kind of elegant guesswork that relies on context. But researchers have deep-sixed that notion again and again, as Mark Seidenberg showed a few years back in his marvelous Language at the Speed of Sight.

Some educators also believe that teaching reading in the same way to all kids according to a set program is too mechanical for a diverse student body with differing skills and predilections, and that learning to read should come through “discovery” and “exploration.” This approach is often titled “balanced literacy,” in which teachers present a class with general strategies but nudge students to help one another learn to read in “reading circles” or via engaging texts on their own, with occasional check-ins from the teacher. The general expectation is that students will marvel their way into reading via assorted individual pathways. That sounds good, and kids from book-lined homes can often manage under this system, but again, Engelmann’s method has worked on kids of all backgrounds. It’s designed to.

As Seidenberg describes in his book, nationwide the phonics and whole-word camps have clashed over and over again, such that some districts use one method and some the other, with many alternating between the two. Some, of course, combine the approaches. But given Engelmann’s findings, this back-and-forth is like a pendulum swing among doctors between penicillin and bed rest. Penicillin is clinical and one-size-fits-all; bed rest allows for improvisation and feels right.