Open-ended Questions
“What” Question:
What – Refers to a noun (object, event, action)
Requirement: A specific noun is required
“Why” Question
Why – reason / cause and effect
Requirement:……(reason / cause)……(effect)
“How” Question
How – Explain the process / method / way
Requirement: Explain the method in terms of
event(s) or action(s) step by step.
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 sensor
shows 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.
Reason
OR
No light is able to pass through more than 6 sheets of
paper.
TB Pg 99 Qn 11
May Ling repeated the experiment by increasing the number
Of sheets of the same type of paper. The table below shows
Her 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
Suggest &
Improve
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.
Pg 10 Qn 39
While 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
a) After a few hours, water was found in the cup.
Describe how water was obtained.
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.
Pg 10 Qn 39
b) 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
b) However, after a few hours, they found that less
water was collected in the bowl. Why did this
happen?
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.
Pg 15 Qn 44
Steven kicks a ball. The diagram shows the path of
the ball after he has kicked it.
Pg 15 Qn 44
a)How can you tell that along the path of the ball,
there is a force acting on the ball?
Ans:
The ball is in constant motion and its direction of movement is ever
changing.
Pg 15 Qn 44
b)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
c) The ball landed on the ground and then rebounded
to a lower height.
Why did the ball reach a lower height?
Ans:
Some energy was converted/ changed to heat and sound energy during
the first bounce, hence the ball rebounded to a lower height.