This blog is managed by Song Hock Chye, author of Improve Your Thinking Skills in Maths (P1-P3 series), which is published and distributed by EPH.

Saturday, January 26, 2008

Algebra allowed but not encouraged

Using Algebra for PSLE Maths is perfectly legal. The student would not be penalized. However, Algebra taught in P6 is very basic. It is not deep enough to solve many of the Section C questions found in PSLE Maths. As such, teachers usually do not encourage students to use Algebra. Instead, heuristics are encouraged.

In P6, only the 4 operations of Algebra is taught. Students are not taught how to use Algebra to solve Section C type questions, which cognitive skills are needed.

As such, if students were use Algebra without being taught how to apply them in actual Section C questions, they may fumble along the way.

Here is an example how Algebra can be used to solve a P6 question.


Ricci saved $200 from her salary and spent the rest. She spent 1/9 of the expenditure on a blouse, $40 on a scarf and the rest on books. The amount spent on the scarf was $20 less than that spent on the blouse. What was her salary?


Let $n be her salary

Since she saved $200, she would have $n - $200 left to spend.

Amount spent on blouse was 1/9 x ($n - $200) = $(n – 200)/9

Amount spent on scarf was $40. But we know scarf was $20 less than blouse, which means blouse cost $60.

Cost of blouse….

$(n – 200)/9 = $60
$(n - 200) = $60 x 9
$n - $200 = $540
$n = $540 + $200
$n = $740

Since $n represents her salary, it means her salary was $740.

Note that there are no diagrams or models used. Every step has to be envisioned in the mind. In the above, you must be able to see that 1/9 of the expenditure is equivalent to the cost of the blouse, which is also equivalent to $40 more than the cost of the scarf . P6 students are not trained to do that using Algebra.

P6 students are however trained in heuristics. Now compare how the same question is done, using heuristics, as demonstrated in the link below.

Tao Nan School P5 SA2 2006 Math Question (Q47)

So to answer the question, “Is Algebra allowed in PSLE Maths?”, the answer is yes, it is, but it is not encouraged.

No comments: