This is a curriculum development as well as a teaching tool that constantly reinforces learning by revisiting a topic several times but at a deeper level each time. It also conceptualizes how the same topic can be approached from many different perspectives. Spiral curriculum can be used for designing large, year-long sets of curriculum or to create a learning journey for a single item in one training course.
This mental model is used explicitly for overall curriculum development in several hours, and then used again and again during instruction.