In this article, we will be analysing the 2018 PSLE Science Exam Paper. We will be sharing the topic weightage for the 2018 PSLE paper as well as discussing 2 interesting questions from booklet B of this paper.

Marks allocated for different topics for Booklet A & B

Table 1: Summary of Booklet A Analysis

Table 2: Summary of Booklet B Analysis

Top 10 topics in 2018 PSLE Science Exam Paper

We have also identified the top 10 topics in 2018 PSLE Science Exam Paper and most of the topics are taught in Upper Primary (Energy and Interactions). Hence it is very important that your child has a firm grasp of the concepts of these topics. Reproduction in plants has the highest weightage in the paper with 11 marks in total.

This is an important topic in Primary 5 and requires the student to remember a lot of content about the plant reproduction processes. Reproduction in plants has been appearing as a highly-weighted topic for the past 5 years in PSLE. Thus it is crucial for your child to be well-versed in this topic.

Other than Reproduction in plants, the other 2 topics that students should pay attention to are Heat Energy and Forces. Students tend to neglect to revise well for Heat Energy as it is a P4 topic. However, concepts about Heat Energy are often tested in PSLE.

Common Topics coming out for Booklet A & B

Table 3: Top 10 topics in 2018 PSLE Science Exam Paper

As shown in Table 3, this paper focuses on these topics Reproduction in Plants, Heat and Temperature, and Forces.  The topic of Electricity is also of high weightage, giving a total of 9 marks (“Using Electricity” and “Electrical System” combined). Hence, this paper is ideal for your child to practise on these topics.

Question Analysis

Most of the open-ended Science exam paper questions on Reproduction in Plants are direct and require little answering technique, hence we would discuss Question 35 and Question 39 instead.

From this, we can learn the tips and answering techniques that are useful for answering questions on Forms and Uses of Energy, Heat and Temperature and Water and Changes of State, which many students tend to struggle with.

The discussion of the Science exam paper questions below will include
1) the recommended answers,
2) explanation of the answers,
3) comments on the answers and
4) tips or answering techniques for the question.

PSLE / 2018 / Q35

Peter has a toy train that runs on batteries. He placed plates of food on the train as shown below.

(a) When he switched on the toy train, it moved along the track. Fill in the boxes below to show the energy conversion as the train is moving. [2]

Answer:    Battery                Wires                     Train

Explanation: Batteries contain chemicals in which energy can be stored. Wires have electric current flowing through it from the battery to the toy train.

Since the toy train moves, kinetic energy is possessed by it. Friction is present between the wheels and the track during the movement will be converted to heat energy and sound energy.

Comments: PSLE accepts “Potential energy” and students need not give “Chemical potential energy”.

Tips: Always put the main form of energy possessed by the object first e.g. “Kinetic energy”, then “Heat/sound energy”

(b) Peter did not change the batteries. Give a reason why the train moved faster as the food was removed. [1]

Answer: When the food was removed the train became lighter and hence, less electrical energy was converted into heat and sound due to friction and more electrical energy was converted into kinetic energy for the train to move faster.

Explanation: The greater the kinetic energy the train possesses, the faster the train moves.

Comments: PSLE requires specific references of the object, which the energy conversion is happening at, were missed out from the answer.

It is better to write: “less electrical energy of the battery was converted into heat and sound energy of the train”, “more electrical energy of the battery was converted into more kinetic energy of the train for the train to move faster.

Tips: Use comparison words such as “lighter”, “less”, and “more” to describe the difference in effects. Use keywords like “converted into” and add references to the energy forms (as mentioned in the comments).

(c) Peter placed a wooden block under the track at point H.

Explain why the train moved more slowly as it moved from G to H. [1]

Answer: Some electrical energy was converted into gravitational potential energy and hence, less electrical energy was converted into kinetic energy and the train moved more slowly.

Explanation: H is positioned higher than G, hence there is more gravitational potential energy at H than at G.

Comments: Again, PSLE requires specific references of the object, which the energy conversion is happening, was missed out from the answer.

It is better to write: “Some electrical energy of the battery was converted into gravitational potential energy of the train, less electrical energy of the battery was converted into kinetic energy of the train ”.

Tips: Use comparison words such as “less”. Use keywords like “converted into” and add references of objects to the energy forms (as mentioned in the comments).

PSLE / 2018 / Q39

A worker used a truck to deliver blocks of ice. A mist was seen when ice was taken out of the truck as shown.

(a) Explain how the mist was formed. [2]

Answer: The water vapour in the surrounding air lost heat to the cooler air that came out of the truck when the ice was taken out. The cooled water vapour condensed and formed fine water droplets as mist.

Explanation: Heat travels from a region of higher temperature to a region of lower temperature. When a gas (water vapour) loses sufficient heat to the surroundings, it condenses into a liquid (water droplets).

Comments: PSLE requires the specific reference of where the water vapour is from – “in the surrounding air”, and where the heat is lost to – “the cooler air”.

Tips: Use keywords like “water vapour”, “ lost heat”,  “condensed” and “water droplets”.

(b) The mist disappeared after a short time. Explain why.  [1]

Answer: The mist took in heat from the warmer surroundings and evaporated to form colourless water vapour.

Explanation: Mist forms when the water vapour loses heat and condenses into fine water droplets, which then gain heat and evaporate.

Comments: PSLE requires a specific reference of where the heat is gained from – “from the warmer surroundings”.

Tips: Use keywords like “gains heat”, “evaporated” and “water vapour”. The answer must link back to the question of why the mist disappeared – “colourless water vapour”.

(c) Thick plastic strips were hung at the door to prevent the ice inside the truck from melting. Explain why. [1]

Answer: The plastic strips helped to keep the cold air inside the truck and prevented warmer air from the surroundings from entering the truck. Hence, the heat flow from the warmer surroundings to the ice to cause it to melt was reduced.

Explanation: Ice melts as it gains heat from its surroundings. When the heat gained by the ice is reduced, the melting of ice is reduced.

Comments: PSLE requires the direction of the heat flow to be specified –“from the warmer surroundings to the ice” and to mention that heat is gained by the ice.

It is better to write: “The plastic strips helped to keep the cold air inside the truck and prevented the warmer air from the surroundings from entering the truck. Hence, the heat flow from the warmer surroundings to the ice was reduced, allowing the ice to gain less heat and cause it to melt slower.”

Tips: Melting suggests that the question is tested on the topics: “Heat and Temperature”, and “Water and Changes of States”. Hence, the answer would require the keyword “gain heat” and use comparison words such as “less” and “slower” to show the change due to the thick plastic strips.

Hope this article benefits your children in writing more accurate and complete answers for the PSLE science questions and that he/she would score better in the examinations. Stay tuned for 2019 Examination Paper Analysis!

Here’s another Primary Science exam paper analysis for you: 2019 PSLE Science Exam Paper Analysis