“Parallel Lessons” Project, organized by the Centre for Educational Leadership (CEL), HKU, aims to improve the quality of learning and teaching through exchange and exploration of teaching cultures of different places. The video-conference was conducted on the 28th February 2017 this year, whereby one of the S5 mathematics classes of College and a class of year 9's from Shanghai Xiwai International School took turns in demonstration lessons on the topic of: Application in Trigonometry. A forum, led by experts with participating teachers from the two locations, was held thereafter.