Last Updated On

Welcome back to our series analysing past year examination papers!

I hope the previous articles have been beneficial to your child’s learning. If you’ve not had the chance to take a look at them, you may do so here:

In today’s article, I will be analysing the 2017 River Valley Primary School (RVPS) P5 SA2 Examination. Once again, I will be sharing with you the topic weightage of the paper, as well as discuss an interesting question I’ve found.

Students who are in Primary 5 would typically learn these topics in school:

• Cells
• Water Cycle
• Reproduction in Humans
• Reproduction in Plants
• Transport in Plants
• Respiratory and Circulatory System
• Electricity

Similar to NYPS, RVPS also taught the topic of Forces in P5. As such, there were 3 questions on Forces in this paper.

The table below is a summary of the weightage of the topics in the 3 papers.

There are a total of 7 questions on Heat Energy in this paper, whereas Electricity has 6 questions! If your child needs extra practice for these topics, RVPS P5 SA2 paper would be ideal for your child to attempt!

## Question Analysis

Since the topics of Heat Energy and Electricity have the highest weightage in this paper, let us take a look at Q36b, which tests on concepts from both of these topics.

*Note: To provide some context to the question, in Circuit B, the heating elements are placed in parallel.

## Background Information

Before we delve into answering this question, have you ever realised that there are lines on the back windscreens of cars? Those are the heating elements. If you’ve realised, have you considered the function of the heating elements?

During heavy rain, water will fall on the front and back windscreens. While there are wipers for the front windscreen to get rid of water droplets, some cars do not have wipers for the back windscreen!

So how do drivers see clearly during heavy rain? This is where the heating elements come into play! When the heating elements are activated via a switch, they would heat up the back windscreen, causing it to become warmer. This causes the water droplets on the back windscreen to gain heat faster from the warmer windscreen and evaporate more quickly. Hence, this allows drivers to have a clear rear view through the mirror in the car.

Other than heavy rain, in what other situation would the heating elements be useful? Do you recall those times when it is extremely warm outdoors and you set the air conditioner in the car to the coldest setting? You’d notice that the back windscreen would become misty after a while! The back windscreen would lose heat to the cooler air in the car and became cooler. The warmer water vapour in the surrounding air would come into contact with the cooler outer surface of the windscreen, lose heat to it and condense to form tiny water droplets. Once again, these water droplets would obstruct the driver’s vision. So what do you have to do now?

Yes, you are right! Just press the button that activates the heating elements! After a short while, the water droplets would evaporate, allowing the driver to have a clear view again! Isn’t the idea of installing heating elements on cars’ back windscreen such a brilliant idea?

## Thought Process

Now that we’ve understood the function of the heating elements, let us proceed with answering the question.

“What are 2 advantages of using Circuit B (heating elements arranged in parallel) to connect the heating elements to the car battery?”

Recall the advantages of connecting objects in a parallel arrangement:

Advantage 1: When one of the objects in the circuit is not working, there will still be a closed circuit with the other objects. Thus, electricity is able to flow through the other objects, allowing them to function.

Advantage 2: Each object can be controlled independently.

Advantage 3: The object will be able to function more effectively. A common example is that the bulbs will be brighter.

Since the heating elements are turned on using only one switch/button in the car, we know that the second advantage is not applicable in this scenario. As such, we will use the first and third advantage answer this question.

The heating elements in Circuit B are connected in parallel.

When one of the heating elements in the circuit is not working, there will still be a closed circuit with the other heating elements.

Thus, electric current is able to flow through the other heating elements, allowing them to heat up the back windscreen.

In addition, the heating elements that are connected in parallel would be able to heat up the back windscreen faster than heating elements that are connected in series. This allows the water droplets on the back windscreen to gain heat faster from the warmer back windscreen and evaporate faster.

## In Conclusion

I hope this article gives you a better idea of how the heating elements on the back windscreen function and what is the best arrangement of connecting them in a circuit!

Stay tuned for more analysis of other past year school papers! 🙂

If you like our methodology, we’ve some upcoming workshops: