Most high schools award credit using a seat-time model. The length of the school year varies by state, but typically students must attend school at least 170 days a year for six hours a day. In this system, teachers typically divide curriculum content over the calendar evenly, but sometimes will slow down to allow more students to achieve mastery, so they are unable to cover all the content. At the end of the term, all students are awarded credit because they have attended the appropriate number of days. The grades are variable, and students earn letter grades using an A-F scale to reflect how well they have mastered the material within the allotted time.

In a mastery-based model, time becomes the fluid piece. Students spend as long as necessary to understand concepts, and if they test poorly, the teacher reviews and reteaches the content. Students have multiple chances to pass assessments, and each attempt informs the teacher how to customize future instruction.

The key to mastery-based learning is that students are held to a high standard. They are not allowed to move forward to new content until they demonstrate mastery. At Brightmont Academy, we define mastery as scoring 80 percent or higher, which is equivalent to a B.

In this environment, teachers expect all students to achieve a B or higher—otherwise they are required to review the material until they are able to meet this standard. Thus, grades are the constant while time becomes the variable. According to Bramante and Colby (2012), "In a competency-based, move-on-when-ready model, there should be no Ds or Fs, and a C should be a rarity."

Under a seat-time model, many factors besides academic performance affect students' grades. Homework, attendance, personality, behavior, and the like sometimes become dominant factors in grading policies, masking the student's level of competency on the skill being measured. A mastery-based instruction model removes these other factors from grading considerations by evaluating the student on whether or not they have mastered the concept being evaluated. This keeps rigor embedded into the instructional model and also ensures that students have the appropriate prerequisite skills, resulting in higher performance, greater self-confidence, and also strong grades.

Bramante, Fred, and Rose Colby. Off the Clock: Moving Education from Time to Competency. Thousand Oaks: Corwin, 2012.