My son will enter elementary school next year, so I feel compelled to revise my primary school maths.

Indeed, the Primary School Leaving Examination (Mathematics) is notorious for testing 12-year-olds questions that leave them stumped in spite of their intense preparations. Several years, students actually come out wailing from the exam hall, their hopes of getting a stellar grade and entering a prestigious secondary school dashed. Well-meaning parents try to coach their children as best as they can, but guess what? Adults often don’t know how to do these questions themselves.

Which explains why I need to prepare in advance and learn the heuristics necessary to excel in this subject. I not only need to ensure that my son knows how to apply formulae, but also have to teach him to be nimble and think non-laterally.

I guess such cognitive exertion and emotional strain do pay off because Singapore has consistently ranked among the top nations in the PISA rankings.

Here’s a question on area and perimeter: