In this article, we will be analysing the 2019 PSLE Science Exam Paper. We will be sharing the topic weightage and discussing 2 thought-provoking 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

Table 3: Top 10 topics in 2019 PSLE Science Exam Paper

As shown in Table 3, this paper focuses on “Man’s Impact on his Environment”, “Forces”, “Heat and Temperature” and “Electrical Systems”.  Hence, this paper is ideal for your child to practise on these topics.

Question Analysis

We would like to discuss the open-ended questions of the above topics. We shall discuss Questions 32 and 38, which we can learn the tips and answering techniques that are useful for answering questions on “Man’s Impact on his Environment”, “Forces” and “Magnets and their properties”, which many students struggle with. For open-ended questions on “Heat and Temperature”, you may want to look at our previous article on 2018 PSLE Science Exam Paper Analysis.

The discussion of the questions below will include
1) the publisher’s answers,
2) explanation of the answers,
3) comments on the answers and
4) tips or answering techniques for the question.

PSLE Science Example Question#1: PSLE / 2019 / Q32

Polar bears are mammals. They swim in the sea to look for food. After some time, they need to get out of the water to breathe and rest on the ice before entering the water again.

(a) Give a reason why polar bears cannot breathe under water. [1]

Answer: Polar bears breathe in air through their lungs.

Explanation: Polar bears are mammals, hence they have lungs. They have neither gills nor moist skin to breathe in water.

Comments: Knowledge-based question which requires a direct answer.

Tips: Recall that breathing methods of animals are introduced in “Diversity of Living Things”- Classifying Animals in P3. Use keywords like “breathe in air” and “through lungs”.

(b) State two forces acting on the polar bear as it walks on the ice. [1]

Answer: Weight of the polar bear and friction between its feet and the ice.

Explanation: Polar bear has mass hence there is gravitational force (weight) acting on it. Friction is a contact force found between two surfaces in contact while the polar bear walks on the ice.

Comments: Since the question ask for forces, it would be better to write “gravitational force acting on the polar bear” instead of “weight of the polar bear”.

Tips: Recall the types of forces and write the relevant forces as the answer. Add in specific references of the object to the type of force, such as “gravitational force acting on the polar bear” and “friction between its feet and the ice”.

(c) Due to global warming, the ice on the surface of sea water decreases in size as shown.

Based on the information given, suggest how global warming affects the survival of polar bears. Explain your answer. [2]

Answer: Due to global warming, temperature increases and the ice melts and becomes thinner. The thin ice will not be able to support the weight of the polar bears on it, may eventually cause the polar bears to drown in the sea water.

NOTE: Some students are not aware that polar bears can drown as they only recalled they are good swimmers.

Explanation: As explained in the Answer. 

Comments: The answer includes the explanation/concept shown in the question/diagram (evidence) – “Due to global warming, temperature increases and the ice melts and becomes thinner.” Followed by the concept linked back to the question on the survival of polar bears – “The thin ice will not be able to support the weight of the polar bears on it, may eventually cause the polar bears to drown in the sea water.”

Tips: Students need to state the evidence and the relevant concept in their answers. To know what the concept is, students can look at part (b) of this question to get clues that the answer is linked to “Forces” – “The thin ice will not be able to support the weight of the polar bears on it”.

PSLE Science Example Question#2: PSLE / 2018 / Q38

Leela placed a magnet on top of a balance as shown in Diagram 1.

She brought object A close to the magnet as shown in Diagram 2.

(a)     State what object A is. [2]

Answer: A magnet.

Explanation: When object A is brought close to the magnet, the reading of the balance increased, showing that there is more force acting on the magnet. Hence, the additional force is due to the repulsion between object A and the magnet. Since only magnets can repel each other, object A is another magnet.

Comments: This question requires direct answer without explanation.

Tips: Look out for “magnet” and “balance” to know that this question is on the topic of “Magnets and its properties” and “Forces”.

(b) Explain why the reading of the balance increased in Diagram 2. [2]

Answer: In Diagram 2, due to the repulsion between the like poles of the two magnets, the magnet exerts a greater push on the top of the balance and hence, the reading of the balance increases.

Explanation: In Diagram 1, only the weight of the magnet exerts a push on the top of the balance. See explanation for part (a) too.

Comments: PSLE does not require students to repeat the result as stated in the question – “the reading of the balance increased”. However, it will be good to use the result to check if the answer written is answered according to the question. 

Tips: Use keywords like “repulsion”, “like poles”, “exerts” and “push”. Use comparison words like “greater” to compare the difference in results after bringing object A close to the magnet.

(c) Leela replaced object A with an iron bar of the same size in the set-up of Diagram 2.

(i) State which reading P, Q, R, S or T, shown below is possible on the balance.

Reading: ______________
Explain your answer. [1]

Answer: P. The iron bar will attract the magnet so it exerts a smaller push on the top of the balance.

Explanation: Iron is a magnetic material that can be attracted by the magnet. Attraction between the magnet and the iron bar is greater than the weight (push) acting on the magnet.

Comments: The answer would be phrased more accurately as such “The attraction between the iron bar and the magnet caused the magnet to exert a smaller push on the top of the balance”.

Tips: Use comparison words like “smaller” and keywords like “attract/attraction”, “exerts” and “push”.

(ii) State a variable that Leela must keep constant when comparing object A and the iron bar. [1]

Answer: The distance between the magnet and object A or iron bar.

Explanation: All variables in the experiment must be kept the same except for the changed variable, which is the iron bar or object A.

Comments: This is an application question which tests students on their understanding of conducting a fair and reliable experiment.

Tips: Identify what has been changed first in the experiment to know what is the changed variable. Students often confused the changed variable with the measured variable whereby the measured values is also changed, but this  is due to the result of the changing the changed variable. The measured variable (results) is another variable which cannot be kept constant in an experiment.

Hope this article benefits your children in writing a more accurate and complete answer for the PSLE science questions and that he/she would score better in the Science exam paper.

Do share this article with your friends and others who can benefit from it 🙂

Here’s another Primary Science exam paper analysis for you: 2017 PSLE Science Exam Paper Analysis