I recently saw a 1954 video of B. F. Skinner showing off a classroom full of eager students using teaching machines. In it, Skinner gave all the usual reasons that teaching machines were soon going to be far superior to ordinary teaching: They were scientifically made to enable students to experience constant success in small steps. They were adapted to students’ needs, so fast students did not need to wait for their slower classmates, and the slower classmates could have the time to solidify their understanding, rather than being whisked from one half-learned topic to the next, never getting a chance to master anything and therefore sinking into greater and greater failure.

Here it is 65 years later and “teaching machines,” now called computer-assisted instruction, are ubiquitous. But are they effective? Computers are certainly effective at teaching students to use technology, but can they teach the core curriculum of elementary…