Spiral curriculum is an approach to education that introduces key concepts to students at a young age and covers these concepts repeatedly, with increasing degrees of complexity. This approach is also known as also known as a "spaced" or "distrubuted" approach. It contrasts with "blocked" or "massed" curricula, which do not introduce difficult concepts until the student has reached a higher level of education.
Nearly any subject can be taught with spiral curriculum. Such curricula break down key concepts into "strands," ideas that are taught year after year, adding to the depth of knowledge each year.
For example, Everyday Mathematics, a curriculum designed with the spiral approach, organizes its lessons around six broad categories (strands) of mathematical concepts that are taught in multiple units each year. Rather than waiting until students have mastered addition, subtraction, multiplication and division, Everyday Mathematics introduces algebraic concepts as early as kindergarten, when students are taught to recognize patterns and find rules governing specific mathematical functions. The curriculum returns to these ideas frequently, adding new information each year and setting higher comprehension goals for each grade level as students gain mastery of the subject.
The idea of spiral curriculum is attributed to Jerome Bruner, who discussed it in his 1960 book, "The Process of Education." Proponents of spiral curriculum say that the approach helps students score better on tests and retain information longer than students who learn from curricula that take a massed approach.