By zapping brains in maths lessons, scientists claim to have boosted students' abilities by a third.
Participants became quicker at calculating and learned up to five times faster, they said.
The Oxford University team gave maths training to 51 students.
Around half of them had a light electrical current passed through their brains as they learned.
After five sessions, those who used the treatment learned new sums and recalled figures, such as times tables, much better than those who did not.