In Rohrer and Taylor's second experiment, students were taught multiple mathematics problem types before practicing them. Practice problems were either grouped into type-specific blocks or randomly mixed. Performance on a test one week later favored mixed practice. This finding concerns practice after initial instruction; it does not show that mixing unfamiliar problems replaces teaching or that mixed practice benefits every subject. The supplied abstract does not establish how much of the advantage came from mixing versus spacing.

Source: Rohrer and Taylor (2007)