Moreover, according to psychologists, the number of 5-6 year olds hospitalised for psychological problems has substantially increased because of parental pressure. "The brains of children at 3-5 years old can absorb only some kinds of knowledge, such as colouring and listening to stories. When they are forced to solve math and write, this affects their physical and mental systems so they can't develop comprehensively. And as their playing time is limited, so are their social skills," says Hanoian psychologist Le Thi Tuy.