Throughout its history, PLATO® Learning has used a mastery-based model to build the content at the heart of its courses and curriculum. PLATO Learning provides semester-long courses on a range of core and elective subjects. Developers start with a curriculum structure built around discrete learning objectives. Then each learning module, or lesson, is focused on one individual objective. Each module includes an introduction to the new material, a chance to practice or apply new knowledge, and an opportunity to demonstrate mastery of the objective before progressing to the next module. This structure is built into units of related material and includes pretests to assess prior knowledge, as well as posttests and end-of-semester tests to confirm mastery for broader levels of content beyond the lesson.