PSLE Science – How to score for structured questions. This part of the article focuses on “explain why” type of questions.

PSLE Science structured questions demand complete and comprehensive answers. 

The most common problem among students is that they are unable to write the keywords that the answer guide provides and hence are unable to score. Other problems include strict marking by Teachers which is rigid and leads to rote learning instead of learning concepts. Refer to this article in news asiaone. In all fairness, I feel that it is necessary to have strict marking for fairness and administrative purpose as Teachers have to mark thousands of scripts.

So how can students try to answer the questions correctly, score the marks that they deserve and without limiting their thinking?

In consultation with a MOE Science Teacher with more than 15 years of marking PSLE science papers, he has this to share:

“The biggest reason why students do not score for PSLE science open ended questions is because they do not phrase their answers properly. I mean, the P6 science concepts are easy to understand. The questions are not rocket science. However students lack the skill to convert the answers in their mind into meaningful, “scorable” output. As such students lose more than half of the marks they deserve due to inability to produce the correct answer. It is then marked as wrong which leads parents and students to think that their Science is lousy. In fact it is their answering technnique that needs bucking up. Not the science. The marking scheme for PSLE Science is fair. We do not mark rigidly word for word as suggested by some.  Instead we will award the score as long as the meaning is correct. Grammar and Spelling mistakes are sometimes not penalised as long as the meaning of the student’s answer is the same as the answer guide. In case of discrepencies we will consult the chief marker and discuss over individual answer scripts.” 

Years of teaching PSLE science taught me that blindly memorising keywords will not work. It stifles creativity and explanation, leading to students answering with single words and not explaining answers properly.

As much as we like to encourage learning, there is a need to learn how to answer questions.

I have broken the answering techniques into several skills, namely:

1. How to “Explain”

2. How to “Give a reason”

3. How to answer “What is the aim”

In this first article on how to score for PSLE science structured questions, we will explore how to answer “explain why” or “explain how” or simply “explain” kind of questions.


EXPLAIN using “start” “end” technique

Explain questions covers at least half of the open ended structured questions. So it is fair to say that if you can explain properly, you will do pretty well.

The technique here is to identify the starting point and end point and fill in the rest.

Let us take a look at some examples.

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For question part a, the starting point is ‘hot buns’. Ending point is ‘became wet’. So…

Start – hot buns

1. Hot water vapour rises

2. Condense on cooler inner surface of box to form water droplets

3. Water drop onto buns

end – buns became wet


For question part b, the starting point is ‘buns in box A’ ending point ‘wetter than buns in box B’

Start – buns in box A

1. Are stored in a box with less holes

2. Less water vapour can escape

3. More water vapour condense to form water droplets

4. More drop down.

End – Wetter than buns in box B



a. Hot water vapour from the buns condensed on the cooler inner surface of the box to form water droplets. The water droplets then drop onto the bun causing it to be wet.

b. There are less holes in box A than box B. This allows less water vapour to escape in box A. When less water vapour escape, more will be condensed into water droplets. More water droplets means the buns in box A will be wetter than buns in box B.


As you can see, our answers will not be too far off from the answer guide by using the start end technique.

Try to identify the start and end points for all the “explain” type of questions below.


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Plant S is most likely to be dispersed by splitting. All the plant S are close to the parent plant and only plants dispersed by splitting will cause this.

Plant R. Plant R has hook like structures that will hook or cling onto the fur of animals living on the island. The animals will disperse it randomly around the island.

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The cloth became wet because water in the sand evaporated and turned into water vapour. The water vapour rose and condensed on the surface of the cloth to form water droplets.

The temperature of air in set up Y decreased over time because as the water in the sand evaporated, it removed heat from the surrounding air. Removing heat will decrease temperature.


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Fluffing up feathers helps to keep the birds warm during cold weather because air trapped in the fluffed up feathers helps to slow down heat loss from the bird’s body to the surrounding.


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By living in empty snail shells, Animal X can protect itself from predators. Predators will not be able to eat Animal X that is hiding in the shell.


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Plant C withered because it cannot photosynthesise. It cannot photosynthesise as both the top and bottom of the leaf is covered with oil which does not allow gaseous exchange. Since the leaf cannot take in carbon dioxide, it cannot photosynthesise to make food. Without food it dies.

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Tube S will have the highest increase in carbon dioxide. This is because both the snail and plant will respire and give out carbon dioxide. The plant gives out carbon dioxide because there is no sunlight to photosynthesise due to the light being blocked.


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  1. Snake F benefits as predators will not eat snake F thinking that it is snake G which is poisonous.
  2. As snake F looks less like snake G over time, the predators will not think it is poisonous and hence feeds on it. This will decrease the population of snake F.

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Object Y


Object Y has a greater volume because the water level is higher as shown in the diagram. The water level is higher as object Y occupies more space than object X.

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The candle possess chemical potential energy














The heat from the candle flame causes the surrounding air to gain heat. The heated air expands and rises. The rising air which is moving causes the spiral to spin.

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  1. Glass is harder than rubber. Therefore rubber cannot scratch glass.
  2. The raised dots increases the surface area of the handle. The increased surface area allows more friction between the worker’s hand and the tool. More friction will help the worker have a better grip.


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b. The boat can throw away some fish so that it could lift off the seabed and move forward.


c. When some of the fish is thrown away, the weight of the boat is reduced. This will cause the boat to rise. When the boat rise, it will not come into contact with the seabed and hence will be able to move forward.




















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