Debunking Conceptual Mistakes in PSLE Science: Part 2

This article is the second in the series of Debunking Conceptual Mistakes in PSLE Science. It is important to clear up any misconceptions that you might have as having correct understanding of Science concepts is the first step to success for PSLE Science.

Misconception 1

The gullet and windpipe are the same tube.

They are located side by side and pupils tend to mistake that they are the same tube.

The truth is…

Gullet belongs to the digestive system while windpipe belongs to the respiratory system. Both are different pipes.

Misconception 2

Blood from the lungs to other parts of the body contains only oxygen.

When we breathe in air, our lungs do not just take in oxygen and filter out all other gases in the air. This is a common misconception that is made in open-ended questions.

The truth is…

Blood from the lungs to other parts of the body also contains other gases like nitrogen and carbon dioxide other than oxygen.

Misconception 3

When there is not enough oxygen in the water, fish swim to the water surface to take in oxygen.

It is a consistent mistake made by most pupils as they think that fish can take in atmospheric oxygen like mammals with lungs.

The truth is…

When there is not enough dissolved oxygen in the water, fish swim to the water surface to take in dissolved oxygen. Note that the gills of fish can only take in dissolved oxygen and not atmospheric oxygen.

Misconception 4

The “white smoke" above the spout of a kettle of boiling water is steam.

Most of us have the experience of seeing white smoke coming out of the spout of a boiling kettle of water and we tend to relate it to a gas.

The truth is…

The “white smoke" above the spout of a kettle of boiling water is actually made up of tiny water droplets when steam condenses on the cooler air above the spout.

Misconception 5

Water vapour is the same as steam.

Since both are in the gaseous state, pupils tend to assume that they are the same and the terms can be used interchangeably. Pupils will be penalised when they make this mistake in a PSLE Science paper.

The truth is…

Steam is formed only when water boils at 100°C. Water can evaporate at a wide range of temperature to become water vapour.

Misconception 6

When ice starts to melt at 0°C, temperature of the ice will increase.

Many pupils have the wrong notions that temperature of an ice cube must be rising if it has started to melt.

The truth is…

When ice starts to melt at 0°C, the temperature of the ice will remain at 0°C till the whole ice cube has melted completely.

Misconception 7

Clouds are made of water vapour.

Many of us, including some adults, think that the clouds in the sky must be in the gaseous state since they can float in the sky.

The truth is…

Clouds are made of tiny water droplets which have gathered together.

Misconception 8

For an open circuit, electricity flows until the part where there is a gap and "flows back" to the battery when it finds that it cannot flow through the gap.

Many of us think that electricity moves in the same way as humans or cars. When we walk to a dead end, we make a U-turn and find another way out.

The truth is…

In an open circuit, electricity will not even flow out from the positive terminal of a battery no matter how far the gap is away from the battery.

Misconception 9

Electricity is "used up" by a bulb in a circuit, so there is less electricity "flowing back" to the battery in the wire after the bulb.

This is a less known misconception that some pupils have.

The truth is…

The amount of electricity flowing before and after the bulb is the same.

Misconception 10

All conductors of electricity are metals.

Most of us tend to associate conductors of electricity with metals only.

The truth is…

Some non-metals like graphite can conduct electricity.

Conclusion

I hope you have benefitted from the list of misconceptions pointed out. Sign up for our coming PSLE Science Revision Workshop in September whereby I will give you a compiled set of notes with more misconceptions explained.

Meanwhile, continue to study wisely and plan a study schedule so that you can revisit all concepts learnt before the PSLE Science paper!