Chinese Math Olympiad (Primary) Trick vs Singapore Modeling Math

Both Methods (I) & (II) below does not use Algebra, which is not taught to primary school kids until secondary school (above 12 or 13 years old).

(I) Ancient Chinese Arithmetic Method:

例2:The sister is 13 years old this year, while the brother is 9 years old.
When the total of their ages is 40, how old will they be?


Trick: Age difference does not change over time, they + or – in tandem. When 2 ages change, the multiple between them also changes.

(II) Singapore Modeling Math:


Compare the Ancient Chinese Arithmetic (I) & Singapore Modeling Math (II):

  • (II) is better for young kids to understand visually the logic behind,
  • (I) is more a memorised trick but poor math education pedagogy. In [例 2] it is very hard for kids to understand why the 2 steps (40+4) & (40 – 4), although they lead to the correct answer.