"After being coached in this way for a year or two, some with a very weak base scored dozens of points more and were admitted to good universities that had been out of reach," Meng said.

Meng charges each student 700 to 800 yuan ($107-122) per hour, which means that a student would pay about 40,000 yuan per year for one class each week. But Meng said it's not much compared with the average level in the industry. "Some teachers may ask for hourly pay of 1,500 or even 2,000 yuan," Meng said.

The high price doesn't seem to frighten away parents. Meng said his small company, without much marketing, got more than 20 clients last year.

Meitong's Zhao said many parents cared more about effects than costs. "Not to mention that sometimes parents can be reimbursed if their children get scholarships," she said.

Zhang Dongdong, a Beijing resident whose daughter got tailored coaching for almost two years, said the expense was worth it. Her daughter, formerly a passive learner, was admitted to a liberal arts college in the United States.

"In large classes, teachers are often distracted by diverse needs of students at different levels, so they can only provide some general knowledge. By comparison, the tailored one-on-one service gives exactly what you need, and the teachers focus solely on you," she said.

"Teachers' attention is a precious resource in class, especially for students like my daughter. We are willing to pay for that attention."