Mohammad Azim Khamosh is known among high-school children in Afghanistan as the country's "most famous teacher". Each week, hundreds of pupils in Kabul take his courses to allow them to continue their education and boost their chances of passing the university entrance exam.
Disillusioned with the standard of teaching in state-run schools and frustrated with the low pay, Mr Khamosh, who began teaching 30 years ago, had wanted to open a private school since the 1980s. But it was only in 2002, when he returned to the country after nine years as a refugee in Pakistan, that he was finally able to open two education centres.
His classes address two main problems, he said. First is the poor quality of textbooks: the ministry of education textbooks are littered with errors and dated in their approach. Mr Khamosh has produced his own books, which he says have eradicated mistakes and offer more in-depth explanations of the subject matter.
The second problem is that, because of the haste to recruit after 2001, many teachers are underqualified. "Go to any school in Kabul and you will see it has a science lab, but they are all locked up," said Mr Khamosh. "There is no one experienced enough to teach."
His courses last two years and are open to pupils in their final two years of school. At present, 1,000 pupils attend the classes. The first year focuses on maths, trigonometry and physics; the second on preparing for the entrance exam by going over past papers. Although he does not teach subjects such as history, geography and Dari literature, Mr Khamosh said that doing the past papers encourages pupils to pay attention in their regular classes.
Pupils must commit to four hours of lessons three times a week and be able to pay 21,500 afghanis (pound;285) for the two years of study. Some scholarships are offered.
Mr Khamosh also presents a maths show three times a week on Education TV, funded by the government. It is broadcast on radio too.
But he said more needs to be done. "From a quantity aspect, I am optimistic: 80 per cent of the country has access to education and they have schools," he said. But quality-wise he was "not optimistic."
He said the government does not pay teachers enough. The base salary is US$120 (pound;78) a month, although, under reforms, pay for high-school teachers will rise to $150-$400 (pound;98-pound;260) a month depending on experience. "(Afghanistan's teachers) are educating the generation of the future, so they should look after them and provide them with support," Mr Khamosh said.