One of the few problems that students have when attempting algebra questions in PSLE Mathematics Paper 2 is that they are unable to figure out the proper heuristics that is needed. Indeed, there questions are pretty basic and fundamental, and it will be paramount for them to understand exactly how to solve the algebra questions. Some parents also commented that while they wish to help their child in this, they are unable to articulate their thoughts out too.

In this article, let us look at an example of a typical algebra question that you can find in PSLE Mathematics Paper 2

## Typical Algebra Questions For PSLE Mathematics Paper 2

In PSLE Mathematics Paper 2, the students will encounter algebraic questions that requires them to form an algebraic expression. This type of question can be solved by two different methods. Of course, the student will be familiar with the Math Model method already. The other method is to solve it simply by using algebra. Let us take a look at an example.

### Example

In this question, a seemingly daunting question is presented to the student. More often than not, the student will stop working on this once they see two triggers. The first trigger is the *word problem* itself. The second trigger is the presence of the letter *r*. Hence, a question of this type is often neglected by students who are unmotivated to attempt

However, if they do attempt to read and ignore the triggers, they will find that it is indeed easy to obtain the correct answer. The student must learn the art of breaking down the questions into simpler forms. This will allow them to have the clarity of mind to solve the question.

#### Step 1: Listing down the facts

The student should first list down the facts that have been presented to them. What is a good way in picking up facts? This might be a potential problem as students might not know exactly what are facts.

To identify the facts, just take a look at the sentences with a number or quantity to it. The factual information should have a quantity to it, or it represents a number. In these cases, *r* and *9* will be the quantity needed.

**Fact 1 : **Sister is *r* years younger than Sharko

**Fact 2: **Sharko is 9 years old.

Once the students are able to list down the facts, they should identify what is wanted by the question.

#### Step 2: Listing down what the question wants and the conditions needed.

While it might sound incredulous that we are writing this, when we quiz the students, some of them could not articulate what is it exactly that the question wants. Also, students often leave their answers in a format that is different from what the question wanted. This is where precious marks can be lost.

**What is needed: **Find the sum of the ages.

**Condition: **Leave answers in terms of *r*.

Once this is done, the students can proceed to solve the question. Now, there are two different methods at solving this question. One of them is the math modelling method, and the other is the algebraic method.

### 1. Solving Using Math Modelling Method

By now, students are perhaps more familiar with using the math modelling method to solve questions. In this method, the student will need to draw out rectangular blocks to represent certain figures. But before they draw the model, they will need to use the different facts that they have listed down. To recap:

**Fact 1 : **Sister is *r* years younger than Sharko

**Fact 2: **Sharko is 9 years old.

With these 2 facts, the student will be able to draw out the model already. This is the model that the student should have drawn.

After drawing the model, the student should look back at what is it that the question exactly wants, and if the answer met the conditions stated. To recall:

**What is needed: **Find the sum of the ages.

**Condition: **Leave answers in terms of *r*.

To find the sum of the ages, it is simple the age of Sharko + the age of Sharko’s sister. Here are the three steps needed to solve the question.

#### Step 1: Find the age of Sharko's baby sister.

From the diagram, it can be seen that the age of Sharko’s baby sister is (9 – *r*) years old.

#### Step 2: Find the sum of their ages.

From the diagram, it can be seen that the sum of the ages is simply adding the green and blue rectangular boxes together.

Sum of the ages

= Sharko’s age and baby sister’s age

= 9 + (9 – r)

= (18 – r) years old

The sum of their ages is **(18 – r) years**.

Wait. We are not yet done. We have to check with the condition listed.

#### Step 3: Check condition

The condition listed was “Leave answers in terms of *r”*. Since our answer is **(18 – r) years**, we have indeed fulfilled the condition given.

Hence, the final answer is that the sum of their ages is at **(18 – r) years. **

Here is a video describing how you can solve the question using the math modelling method.

### 2. Algebraic Method

When using the algebraic method, it is actually much simpler than thought. To recap, here are the notes that we have taken.

**Fact 1 : **Sister is *r* years younger than Sharko

**Fact 2: **Sharko is 9 years old.

**What is needed: **Find the sum of the ages.

**Condition: **Leave answers in terms of *r*.

With these information, we can proceed to form algebraic expressions to solve the problem

#### Step 1: Form algebraic expressions from facts

For fact 1, since the sister is *r* years younger than Sharko, and Sharko is 9 years old, then it means that the sister is (9 – *r*) years old.

Hence, sister’s age = (9 – *r*) years old.

#### Step 2: Find the sum of the ages

Sum of the ages

= Sharko’s age and baby sister’s age

= 9 + (9 – r)

= (18 – r) years old

Hence, the sum of their ages is (18 – r).

Do remember to check with the condition listed too.

## Summary

As a summary, when you wish to solve simple PSLE algebra questions, there are two ways to solve the PSLE algebra questions. It is entirely up to the student to decide which method works best for them.

However, both methods requires the student to breakdown the question into simpler parts. By listing down the factual information and the condition, it will be much easier for the student to understand the question itself. With this information armed, your child will be able to attempt the questions listed in the PSLE mathematics paper with ease.