More than 770,000 untrained teachers are working in India's state schools, according to government figures, with education experts suggesting that one in five teaching positions is vacant.
To deal with the problem, ministers have allocated #163;2.9 billion over the next five years to get more qualified teachers into the system. But a scheme that trains highly motivated graduates and professionals and places them in some of India's poorest schools has yet to receive government money or accreditation.
Teach For India, based on Teach For America and Teach First in the UK, placed its first teachers in schools in Pune and Mumbai in June 2009. The charity, like its US and UK counterparts, provides intensive training and support over two years.
Shaheen Mistri, Teach For India's founder and chief executive, said that the model could be used to help alleviate the chronic shortage of trained teachers in India.
"For those who are already teaching and don't have training, the system of learning while teaching could be very effective when we are looking at the scale of India's problem with training," Ms Mistri said. "There's an urgent need to allow different routes to teacher certification - not bringing down the bar but saying that you don't necessarily need two years at bachelor of education college to become a trained teacher."
Because Teach For India fellows do not have a formal government-recognised teaching qualification, they are not eligible to be on schools' payrolls, and are instead paid by the charity.
The Right to Education Act has driven the demand for more teachers. The law, enacted three years ago this month, made it compulsory for six- to 14-year-olds to attend school and for teacher-student ratios to be capped at one to 30. The deadline for implementation passed at the end of March but, according to education charities, about 300,000 schools failed to comply in terms of school infrastructure and teacher quality.
In many of the classrooms where Teach For India fellows work, 75-80 children sit four or five to a bench and attend in shifts because demand is so high.
"Very often, pupils get only two and a half hours of proper instruction per day, which is completely crazy when many are four or five years behind in their learning," Ms Mistri said.
The fellows are encouraged to keep their students behind for extra lesson time after school but it is difficult when there is little classroom space and time in their schedule, she added.
Former Teach For India participants support the fellows, whose average age is 23, providing mentoring and feedback on lessons. Ms Mistri hopes that 2,000 fellows will be participating in the scheme by 2015-16 but acknowledges that this is a tiny number compared with India's requirements.
"It's about creating a movement of leaders who in 10 to 15 years' time will continue to fight for equality in education wherever they are," she said.
Alumni are already going on to set up schools in impoverished parts of India, Ms Mistri added. "Each one leaves the programme with the mindset that they can bring change in education."