The teaching of Putonghua has helped raise the Chinese language standard of local primary school students, a study has revealed. Six primary schools took part in the five-year survey, conducted by Primary Chinese Language Education Research Association. In each school, one Primary Three class was taught in Putonghua and another in Cantonese. The classes were taught by the same teacher. The arrangement continued until the students graduated. From 2000 to 2002, the two classes took a total of seven tests. The average score of the Putonghua classes was higher than the Cantonese ones in every test. Students in the Putonghua classes had much stronger writing and comprehension skills and a more extensive vocabulary. Lau Siu-ling, chairperson of the association, said the study indicated Hong Kong should teach Chinese lessons using Putonghua. She suggested that schools use Putonghua to teach Chinese from Primary Two, along with lessons on Putonghua pinyin. But the chairman of the Standing Committee on Language Education and Research, Michael Tien Puk-sun, stressed that changing the teaching medium could have profound effects on students. He said officials would have to think hard before making any changes. The committee is also conducting research on the benefits of Putonghua lessons in 20 secondary and primary schools.