In 1984 Benjamin Bloom published a groundbreaking paper: the 2-Sigma experiment. He aimed to demonstrate that personalised instruction leads to better educational outcomes. The results are astonishing, and 2-Sigma became essentially a brochure for private tutoring.

American educational psychologist, Benjamin Bloom, devised the 2-Sigma experiment in the 1980s as part of his wider research into different educational methods and their impacts on student performance.

He wanted to find out if teaching students one-on-one or making sure they really understand each topic before moving on would help them do better than the usual way of teaching.

Here's what he found:

• Students who had their own tutor did far better than students in regular classes. In fact, the average student who was tutored did better than 98% of students in a normal class setting.
• Students in mastery learning classes also did better than those in regular classes, showing that even in group settings, making sure everyone really understands the material can make a big difference.

Bloom didn’t only prove his hypothesis. The results were staggering, and his research spawned several key insights and theoretical frameworks regarding the effectiveness of one-on-one tutoring compared to traditional classroom education.

Take a look at this short video of Victoria Gibbs, our COO, at the Prestel & Partner Forum last year, explaining the 2-Sigma research.

The experiment: classroom vs mastery vs private tutoring

Quite simply, Bloom wanted to demonstrate the impact of personalised instruction and the potential of mastery learning (even within group settings) to significantly improve student outcomes.

To do this, his methodology involved comparing the educational outcomes of students across three distinct instructional settings:

1. Conventional classroom instruction: This was the standard group-based teaching method used in most educational settings, where one teacher instructs a group of students simultaneously, typically following a uniform curriculum.
2. Mastery learning: In this method, students were still taught in a group setting but with a key difference. Instruction was designed so that all students were required to achieve a high level of understanding (mastery) of a topic before moving on to the next. This approach often incorporated formative assessments, feedback, and additional study time for topics as needed.
3. One-on-one tutoring: Students received personalised instruction from tutors. The tutoring was highly individualised, allowing for immediate feedback, customised pacing, and instruction tailored to the student's specific needs and learning style.

And the results?

Bloom's findings were striking. He found that students who received one-on-one tutoring performed significantly better than those in conventional classroom settings, with tutored students achieving average scores that were two standard deviations (the "2 Sigma") higher than the average for classroom-taught students. This meant that the average tutored student outperformed 98% of the students in the traditional classroom setting.

Furthermore, mastery learning students also showed significant improvement over traditional methods, though not as dramatic as the one-on-one tutored students. These results demonstrated the profound potential of personalised learning approaches to enhance educational outcomes significantly.

It's important to note that Bloom's findings were more about illustrating the potential benefits of individualised instruction and the concept of mastery learning rather than providing a bulleted list of outcomes.

Are there any challenges to his research?

It's rare to find direct disagreements with Bloom's 2-Sigma study in educational discussions. Mostly, people talk about the challenges in applying his ideas everywhere because of resource issues:

• Making it work for everyone: The biggest problem with using Bloom's approach for all students is that it needs a lot of resources - it's not feasible to give every student their own tutor!
• Not all tutoring is equally effective: How well it works can depend on how good the tutor is, what they're teaching, and what the student needs help with.
• Improving learning for groups: Researchers are looking at different teaching methods that can make learning more personal for everyone, even in larger class groups.

The 2-Sigma case for full-time private tutoring

Private tutoring and full-time homeschooling align closely with Benjamin Bloom's 2-Sigma findings by inherently providing the highly personalised and individualised instruction that Bloom found to be so effective.

Let’s reiterate why full-time private tutoring works so well, according to Bloom's findings:

• Personalised teaching: Private tutoring means instruction can be tailored to the student's learning pace, style, and interests, which Bloom found most effective, and allowing students to master topics before moving on.
• Mastery learning: Private tutoring easily incorporates mastery learning principles, ensuring that a student fully understands a concept before progressing.
• Immediate feedback and correction: A private tutor can help students understand their mistakes and learn from them quickly, reinforcing learning and mastery of subjects.
• Increased engagement and motivation: With the ability to customize lessons to a student's interests, private tutoring can increase engagement and motivation, making learning more relevant and exciting.
• Emotional and psychological support: The one-on-one nature of tutoring can provide strong emotional support, boosting students' confidence, reducing anxiety around learning, and fostering a positive attitude towards education.
• Educational outcomes: Echoing Bloom's 2-Sigma findings, students who receive private tutoring often show improvements in academic performance, scoring higher on standardised tests and demonstrating better understanding of subjects compared to their class-schooled peers.
• Flexibility and adaptability: Private tutoring offers the flexibility to adapt learning schedules, formats, and content to best suit the student's needs.

Bloom’s groundbreaking research suggested profound implications for educational practices, advocating for personalised teaching that considers the individual needs and learning paces of students to maximise their educational outcomes.

Private tutoring can achieve the kind of learning improvements that Bloom identified in his research, by focusing on the individual needs of each student, aligning with their strengths, and ensuring students are engaged, given immediate feedback, and can master a topic before moving on to the next.