«The textbooks my students use follow a formula. A chapter will introduce a new concept and related procedures. At the end of the chapter will be a number of questions related to the concept for students to answer. Drank neat, this is not interleaving».
«There is growing evidence that the effectiveness of retrieval practice, distributed practice and all those other ways of introducing desirable difficulties depend on element interactivity.
The initial experiments in many of these areas were conducted using relatively simple tasks such as learning lists of words. However, when we move to more complex tasks, we start to see a difference emerge between relative novices and relative experts. In a recent experiment, variation of task was found to be beneficial for relative experts but not for novices.
It may be the case that the textbooks have it right after all. When first meeting a complex concept, there may be enough difficulties for students to attend to without introducing supposedly desirable ones».