“What” Question:What – Refers to a noun (object, event, action)Requirement: A specific noun is required

“Why” QuestionWhy – reason / cause and effectRequirement:……(reason / cause)……(effect)

“How” Question How – Explain the process / method / wayRequirement: Explain the method in terms of event(s) or action(s) step by step.

Open-ended QuestionsOpen-ended QuestionsOpen-ended QuestionsOpen-ended Questions

Pg 99 Qn 11

May Ling designed a model to count sheets of paper.

a) When no paper is placed at position X, the light sensorshows a reading of 80 units. When a sheet of thin paper is placed at X, the reading becomes 32 units. Give a reason for this observation.Ans:The sheet of paper is translucent and blocks some of the light from the torch entering the light sensor.

Pg 99 Qn 11

b) Give a reason why the set-up cannot be used to count more than 6 sheets of the paper.

Ans:The intensity of the light is not strong enough to pass through more than 6 sheets of paper.

ORNo light is able to pass through more than 6 sheets of paper.

Reason

TB Pg 99 Qn 11May Ling repeated the experiment by increasing the numberOf sheets of the same type of paper. The table below showsHer results.

Number of sheets Amount of light (units)

0 80

1 32

2 13

3 5

4 2

5 1

6 0

7 0

8 0

Pg 99 Qn 11

c) Describe one change that May Ling can make to the model if she wants to count up to 8 sheets of the same type of paper.

Ans:She can put the torch nearer to the papers or the light sensor

OR

She can use a torch which gives out a brighter light/ light intensity such that the amount of light that can be detected without any sheet of paper is more than 80 units.

Suggest & Improve

Pg 10 Qn 39While camping at Changi beach on a hot day, a group of students performed an experiment to obtain water from sea water. The dug a hole in the ground and lined it with a plastic sheet. Another plastic sheet was used to cover the set-up. Some rocks and a stone were placed as shown.

Pg 10 Qn 39

Ans:Sea water evaporated into water vapour which rose to the plastic sheet. When the warm water vapour came into contact with the cooler inner surface of the plastic sheet, it condensed into water droplets. The stone placed in the middle of the plastic sheet allowed the water droplets to flow along the side of the plastic sheet and drip into the cup.

a) After a few hours, water was found in the cup. Describe how water was obtained.

Pg 10 Qn 39b) Another group of students did a similar experiment with the same amount of sea water in the hole. Instead of a cup, they used a large bowl to collect water as shown below.

Pg 10 Qn 39

Ans:The bowl had a wider base area and top opening, leaving little empty space for the sea water to evaporate. Less water would be able to evaporate and rise to condense on the cooler inner surface of the plastic sheet, so less water was collected.

b) However, after a few hours, they found that less water was collected in the bowl. Why did this happen?

Pg 15 Qn 44Steven kicks a ball. The diagram shows the path of the ball after he has kicked it.

Pg 15 Qn 44

Ans: The ball is in constant motion and its direction of movement is ever changing.

a)How can you tell that along the path of the ball, there is a force acting on the ball?

Pg 15 Qn 44b)If the boy kicked a heavier ball with the same force and in the same direction, draw the path of this ball on the diagram using the same starting point Y.

Pg 15 Qn 44

Ans:Some energy was converted/ changed to heat and sound energy during the first bounce, hence the ball rebounded to a lower height.

c) The ball landed on the ground and then rebounded to a lower height.Why did the ball reach a lower height?