How social mixing in schools is defined and measured determines how student diversity is evaluated, and it is therefore worth challenging Education Minister Ong Ye Kung’s claim that “the social mix of students in Integrated Programme (IP) schools is actually better than that in non-IP schools” (ST, Dec. 27). The metric used by the Ministry of Education (MOE) is that “every 100 Secondary 1 students in a school should come from 20 or more primary schools”. A school with 300 secondary one students, as inferred, should have these students hailing from at least 60 different primary schools. Based on this too, MOE should be able to track the total number of primary schools represented in each secondary school’s secondary one cohort.