Mastery learning is an instructional strategy and educational philosophy that emphasizes the importance of students achieving a high level of competence (e.g., 90% accuracy) in prerequisite knowledge before moving on to new material. This approach involves providing students with individualized support and repeated opportunities to demonstrate mastery through assessments. If a student does not initially achieve mastery, they receive additional instruction and support until they do. Mastery learning is based on the idea that all students can learn effectively with appropriate instruction and sufficient time, and it contrasts with traditional teaching methods that often focus on covering a set amount of material within a fixed timeframe, regardless of individual student needs.

Mastery learning (or, as it was initially called, "learning for mastery"; also known as "mastery-based learning") is an instructional strategy and educational philosophy, first formally proposed by Benjamin Bloom in 1968. Mastery learning maintains that students must achieve a level of mastery (e.g., 90% on a knowledge test) in prerequisite knowledge before moving forward to learn subsequent information. If a student does not achieve mastery on the test, they are given additional support in learning and reviewing the information and then tested again. This cycle continues until the learner accomplishes mastery, and they may then move on to the next stage. In a self-paced online learning environment, students study the material and take assessments. If they make mistakes, the system provides insightful explanations and directs them to revisit the relevant sections. They then answer different questions on the same material, and this cycle repeats until they reach the established mastery threshold. Only then can they move on to subsequent learning modules, assessments, or certifications.

Mastery-based learning methods emphasize that instruction should be tailored to the individual time needed for each student to master the same content. This is very much in contrast with classic models of teaching that focus on varying student abilities and allocation of equal time and instructions irrespective of the students' unique needs. Mastery learning shifts the perspective, attributing student challenges to instructional methods rather than inherent abilities. This underscores the importance of individualized teacher-student interactions over group evaluations. Therefore, the task in mastery learning is to ensure sufficient time and employ effective instructional strategies so that all students can achieve the same level of learning. This learner-centered approach also aligns with andragogy principles as well, recognizing that adult learners benefit from tailored instruction and assessments that are inclusive and supportive, fostering a fair and non-oppressive learning experience.

Since its conception, mastery learning has empirically been demonstrated to be effective in improving education outcomes in a variety of settings. Its effectiveness is influenced by the subject being taught, whether testing is designed locally or nationally, course pace and the amount of feedback provided to students. Research has identified an average effect size of 0.59, which demonstrates moderate to substantial improvements in academic performance with Mastery Learning. Higher mastery thresholds have been associated with greater improvements in examination performance, and the use of targeted feedback has been shown to address learning gaps and misconceptions effectively. Additionally, since the model uses elements such as autonomy and competence, which are thought to enhance student motivation and engagement, this is said to be another reason for the potential success of the model in specific circumstances.

The motivation for mastery learning comes from trying to reduce achievement gaps for students in average school classrooms. During the 1960s John B. Carroll and Benjamin S. Bloom pointed out that, if students are normally distributed with respect to aptitude for a subject and if they are provided uniform instruction (in terms of quality and learning time), then achievement level at completion of the subject is also expected to be normally distributed. This can be illustrated as shown below:

Mastery Learning approaches propose that, if each learner were to receive optimal quality of instruction and as much learning time as they require, then a majority of students could be expected to attain mastery. This situation would be represented as follows:

In many situations educators preemptively use the normal curve for grading students. Bloom was critical of this usage, condemning it because it creates expectation by the teachers that some students will naturally be successful while others will not. Bloom defended that, if educators are effective, the distribution of achievement could and should be very different from the normal curve. Bloom proposed Mastery Learning as a way to address this. He believed that by using his approach, the majority of students (more than 90 percent) would achieve successful and rewarding learning. As an added advantage, Mastery Learning was also thought to create more positive interest and attitude towards the subject learned if compared with usual classroom methods.

Individualized instruction has some elements in common with mastery learning, although it dispenses with group activities in favor of allowing more capable or more motivated students to progress ahead of others while maximizing teacher interaction with those students who need the most assistance.