01

Mastery learning is the concept that students must master the foundational subjects or concepts before moving on. It’s based on the fact that all learning builds on itself. As Sal Khan of Kahn Academy explains in this TED talk on mastery learning, in his decades of tutoring students he found a similar pattern. Many students struggle not because they are “not good at math,” but just because they had gaps in their learning.
## Mastery learning is the concept

“They are in an Algebra class and they might have been a little bit shaky on the pre-algebra, and because of that they thought they didn’t have the math gene. Or they are in a calculus class, but they are a little bit shaky on the algebra” – Sal Khan
These gaps accumulate over time, so that math becomes harder and harder. Eventually, many students start believing ‘they are just not good at math’ and stop trying. This in turn, yields more gaps.

02

In all other areas of life, when you are required to complete a task, or learn a skill, you do it when you have mastered the preceding material. If you learn guitar, you try to play a song after you learn the chords to it. If you play soccer, you advance to Varsity after you do well enough on JV. If you build a house, you build the first floor after you are done with the foundation.
In all areas, except the standard school system, people advance based on skill or results. In standard school, students advance based on time. Students are grouped by age, and all move together at the same pace, irrespective of their level. If you get a C in 5th grade science, you still move to 6th grade science. Sal Khan gives a more concrete example:
## Mastery-Based vs Time-Based

“Let’s say we’re in middle school pre-algebra. The teacher will give a lecture on exponents, then we’ll go home and do some homework… and that will continue for about 2 or 3 weeks, and then we get a test. And on that test, maybe I get a 75%, maybe you get a 90%, maybe you get a 75%… even though that test has identified gaps in our knowledge, the whole class will then move on to the next subject, probably a more advanced subject like negative exponents. You immediately start to realize how strange this is – I didn’t know 25% of the foundational thing, now I’m being pushed to the more advanced thing. And this will continue for months and years until I am in a geometry class and I hit a wall. – and become disengaged.” – Sal Khan

Just like you would not build a house on a foundation that is only 80% complete, it does not make sense to ask students to build on material that they have only partially learned. If you’re not quite convinced, let’s look at the science. Dozens of studies dating back decades have shown that students do not only learn with greater efficacy and retention with a mastery-based approach, but also learn faster. That’s because they have a stronger foundation for more advanced material later on. You can find a selection of studies here, but we outline a few below:
**Indiana University (1975)**

**UC Santa Barbara (1976)**

**University of Kentucky (2001)**