“Spiral learning” is a rationalization for ineffective pedagogy and a self-fulfilling prophesy of poor educational outcomes.
The idea of spiral learning is that students should learn the basics of a topic without getting into details, then come back to it later, deepening their understanding while reinforcing the basics. It’s hard to object to that. And many of us recognize the pattern, in our own education, of struggling with a topic on the first attempt and really getting it only after several iterations.
The problem is that the spiral approach suggests that students will not understand a topic well on the first pass, and that teachers should not expect them to. But many students are discouraged by half-understood classes, and teachers’ low expectations can cause the outcomes they predict.
There is a related problem in software engineering. In 1975, Fred Brooks observed that many software teams build an implementation before they understand the problem, re-write the specification, discard the first implementation, and then implement the revised spec. He suggested that project managers expect to discard the first implementation, and proposed what became the software mantra, “Plan to throw one away; you will, anyhow.”
This sounds like good advice, but in the evolution of software engineering, it has been widely rejected. Craig Zerouni pointed out the trap: “If you plan to throw one away, you will throw away two.” And in the most recent version of his book, Brooks recants his recommendation.
Similarly, if you expect students not to understand a topic the first time it is taught, they won’t understand it the second time, either. The notion that students will have to come back to a topic for full understanding becomes an excuse not to teach it well the first time.
Worse, when students are unhappy because they don’t understand their classes, faculty who invoke the principle of spiral learning can be resistant to feedback and desensitized to symptoms of failing pedagogy.
If “spiral learning” means that introductory material appears again with more sophistication later in the curriculum, there’s nothing wrong with that. But at each step, teachers should have an accurate expectation of the understanding students will achieve (with appropriate preparation and effort). Most students should meet that expectation, and a student who does not should express dissatisfaction and seek remedy, without being told to wait until the next time around on the spiral.