The key finding was that students’ general cognitive abilities interact with the level of structure provided by the teacher: students who score lower on measures of general ability do better in teacher-controlled learning environments, in which teachers maintain a high level of control, lessons are broken down into small units, with direct instruction and frequent feedback. The contrary holds for students with higher general ability, who benefit from so-called discovery or learner-centred learning environments. The concept of “adaptive teaching” was a response to this realisation in which teachers are seen as best able to make moment-to-moment decisions about what works for each of their students. As learners gain in aptitude through experience with respect to the instructional goals at hand, such teaching adapts by becoming less intrusive.