There have been widespread concerns about Hong Kong students' lack of awareness of their national identity, which many attributed to the fact that Chinese history was previously not a compulsory subject in local schools.

Some also worry that teaching of Liberal Studies has made students more radical because when there are no official teaching materials, students can be influenced by teachers with strong political views.

But Secretary for Education Kevin Yeung Yun-hung is not so sure. "We cannot conclude that Liberal Studies played a big part in the social unrest in Hong Kong,'' he told China Daily. "But it is time for a review after it has been a compulsory subject for nearly 10 years."

Liberal Studies has a general curriculum with six modules, but teachers have always been preparing teaching notes in the absence of a formal syllabus and textbooks, Yeung explained.

Several publishers have been publishing teaching notes to aid teachers, but the content was not examined by the Education Bureau.

"Last September, seven publishers agreed with the bureau to send these teaching notes to a committee comprising education officials and academics. If the committee has any suggestions, the publishers will revise the next editions, which will be put into use in the next school year in September," he disclosed.

For teaching materials developed by teachers, it is mainly up to the schools to examine the content. "If we receive complaints that the teaching materials are biased or do not match students' abilities, we will look into this and talk to the schools," he said.

Chinese history is a compulsory subject for secondary one to three students. "At present, history up to the end of the Qing Dynasty (1644-1911) or the beginning of modern China in 1949 is taught in junior secondary classes," he said.

"From September, the scope will be widened and lengthened; more contemporary history will be taught. The curriculum will become more selective, with a focus on major historical events, while some dynasties may be skipped," Yeung added.