Bloom's 2 Sigma Problem and Blended Learning in African Schools

David Fair
Jun 16
3 min read

How Technology Can Unlock Every Learner’s Potential

In 1984, renowned educational psychologist Benjamin Bloom made a ground-breaking discovery; students who received one-on-one tutoring with mastery learning outperformed 98% of those in traditional classrooms. This became known as the ‘2 Sigma Problem’ – ‘2 sigma’ refers to the two standard deviations’ level of improvement that tutoring achieved over standard instruction.

In real terms, this meant that the average tutored student outperformed 98% of students taught in a conventional manner.

Why did tutoring work so well? It offered:

Personalised attention
Immediate feedback
The chance to learn at your own pace

However, while tutoring is impactful, it’s also expensive and impractical to implement broadly especially in parts of Africa where classrooms often have over 60 learners. As a result, Edulution has been wrestling with the critical question: how do we replicate the benefits of tutoring at scale?

The answer: blended learning powered by educational technology.

Children using AI EdTech facilitated by Edulution Blended Learning in classroom in Africa.

The Challenge in African Classrooms

To understand why blended learning matters, we need to look at what many sub-Saharan African schools face:

Overcrowded classrooms: One teacher, 60+ students. Enough said.
Multigrade learning levels: Many learners are 1–3 grades behind, therefore teaching one level is nearly impossible.
Limited teaching resources: Few textbooks, outdated materials, and little to no manipulatives.
Inadequate teacher training: Especially in maths and differentiated instruction.
Weak learning outcomes: Foundational maths and literacy skills are worryingly low.

This creates the exact opposite of Bloom’s ideal environment.

Blended Learning: A Scalable Alternative to Tutoring

Blended learning doesn’t just add devices to classrooms - it reimagines how learning happens. By combining face-to-face teaching with digital tools, it enables personalisation, saves teacher time, and offers better feedback loops.

Here’s how:

1. Personalised Learning Through Adaptive Tech

AI-driven tools like Mindspark adapt content based on each learner’s level. Edulution uses this system to deliver structured maths lessons allowing learners to progress at their own pace.

A Grade 5 learner who’s behind can work on Grade 3 content without shame.
A high-flyer can move ahead, unhindered by slower peers.

Just like tutoring - but broader.

2. Smarter Use of Teacher Time

In a station rotation model, students cycle through:

Independent work on tablets
Direct instruction from the teacher
Peer learning or group work

With help from trained educator assistants, teachers can give focused support to small groups. It's not one-on-one tutoring - but it’s significantly closer than whole-class teaching.

3. Instant Feedback and Actionable Data

Platforms like Mindspark give learners instant feedback and provide teachers with real-time insights into each learner’s progress.

Teachers no longer need to spend hours marking.
Teachers can identify and support struggling learners early – this is key to mastery learning.

4. Reach and Equity

Digital content can be shared widely at minimal cost. Edulution even runs offline, allowing rural learners to access high-quality content without internet access.

What’s Needed to Make This Work?

Edulution is working to realise the potential of blended learning, by ensuring certain foundations are in place:

Teacher training and support – technology will never replace teachers, but training is needed to empower them to use technology effectively.
Local educator assistants – recruited from the community, supporting the teacher and removing logistical challenges in the classroom, making the model sustainable and culturally rooted.
Useful data streams – learner activity must feed into live dashboards that inform teacher decisions about where and when to intervene.
The correct infrastructure – robust affordable devices, electricity (solar where needed), and secure storage.
Localised content – must align with the national curriculum and eventually be available in home languages.
Community involvement – parents and leaders need to be part of the journey.