The effects of the handover came slowly but surely for Hong Kong's teachers, with the biggest challenges rolled out in the education reforms that started in the early 2000s. Ng Wai-ching and Cheung Yuen-sum witnessed their school, Tai Po Old Market Public School, switch from teaching Cantonese to Putonghua for Chinese classes, and both have first-hand experience of how the job has changed since then.
Over the years, the mode of teaching has also changed to a more interactive model - in contrast to older rote-based methods - with the school providing more opportunities for students to get wider experience and exposure. But the changes have also created new challenges for teachers.
'Actually, the education reforms increased teachers' workload considerably,' says Ng, who has been teaching for 20 years.
Starting as a teacher of Chinese and mathematics, Ng did not have Putonghua credentials at first. After the handover, she decided to change that. After taking the first course in 1998, Ng did not stop studying until she had gained her qualifications to teach in Putonghua in 2004.
It was a demanding process. 'It was really tough. I was teaching in school all day, then prepping for the next day's lessons until 6pm. Then I left school to go to school again - for continuing education classes. It was school non-stop.'
Cheung had a different experience because she took Putonghua as an elective at university. She took a language immersion programme in Beijing for a few months while at university and was a qualified Putonghua teacher by the time she graduated. Cheung was one of the pioneering teachers at the school, teaching Putonghua to the first group of Primary One students.
Tai Po Old Market Public School started teaching Chinese lessons in Putonghua to Primary One classes in 2004. By 2010, all Chinese language instruction was in Putonghua. Students were quick to make the adjustment, Cheung said. 'In the beginning we mixed a bit of Cantonese in, but the students got the hang of it very quickly, and feedback from them told us that they enjoyed it,' she says.