This usually comes up in August, during the long vacation. It is basically for the examination classes (Year 9 & Year 12) in preparation for Cambridge Checkpoint and IGCSE examinations.
In addition, students with offer of admission into Year 7 are also encouraged to attend the Summer School for purposes of acclimatization since majority of the students coming into Year 7 would be leaving home for the first time.
The Summer School usually last for four weeks with the exception of the acclimatization programme for Year 7 which is for two weeks. Generally, the Summer School programme has been a huge success over the years.