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?

【这位妈妈太绝了！竟把小学6年奥数化为13句口诀】

*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**:

**［例2］**

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.

Notes:

- Singapore Modeling Math (II) is invented by the Singapore Professor Lee Peng Yee 李秉彝 from Nanyang Technological University (National Institute of Education) in the 1980s, combining: Ancient Chinese Arithmetic [as shown in (I)], Polya Problem Solving Methodology, Visual Graphical Modeling
- French Fields Medalist Cédric Villani recommended the Singapore Modeling Math Pedagogy to all primary schools in France.

- The most famous Chinese Ancient Arithmetic “The Chicken-Rabbit Problem” (《孙子算经》，dated 3 AD – 5 AD）which had inspired Prof Lee Peng Yee. Watch video “鸡兔问题 :“.

https://tomcircle.wordpress.com/2019/03/14/chinese-math-olympiad-primary-trick/

- The Physics Noble Prize Laureate Paul Dirac’s “Coconuts & Monkeys Problem” : use Higher Math (Sequence & Linear Algebra, solved by Prof Richard Halmos) vs Singapore Modeling Math (3rd solution) .