Bloom's problem was cost, and since 2023 a patient, always-available tutor has become nearly free. The finale weighs Khanmigo, a 2025 Harvard randomized trial and a Nigerian pilot against hallucination, cognitive offloading, privacy and equity, asking what using AI right requires.
Who's who
- Benjamin S. Bloom+1 more episodeEducational psychologist whose 1984 two-sigma finding set the problem
- Salman KhanFounder of Khan Academy; launched the GPT-4 tutor Khanmigo in 2023
- Gregory KestinHarvard physics lecturer behind the 2025 AI tutoring randomized trial
- Martin De SimoneWorld Bank researcher who led the Edo State, Nigeria tutoring pilot
- Federico TibertiWorld Bank researcher on the Nigeria pilot
- Kristen DiCerboKhan Academy chief learning officer urging schools to gather their own evidence
Where it happens
- Edo State, NigeriaSite of an after-school GPT-4 tutoring pilot with large reported gains
- Harvard University, Massachusetts+1 more episodeSite of the physics experiment comparing AI tutoring with active learning
Timeline
- 1984Bloom publishes the 2 Sigma Problem, concluding one-to-one tutoring is too costly
- March 2023GPT-4 released and Khan Academy launches Khanmigo as a limited pilot
- May 2024Khan publishes Brave New Words on AI and education
- January 29, 20252024 Nation's Report Card shows reading down again in grades 4 and 8
- c. June 2025Kestin and colleagues publish AI Tutoring Outperforms Active Learning in Scientific Reports
Still debated
The Harvard trial is clean but narrow, and whether its effect holds across a semester, ordinary students and unsupervised use is unknown. Whether AI builds thinking or replaces it, and whether it closes or widens gaps, are open questions.