Q&A - PSLE Science

[ADoc]

anneshirleygilbert:

Thank you, ADoc. The glossary is very detailed and helpful. Will surley heed your advice about answering within the realm of Spore Primary Science syllabus. Thanks again.

cheers anneshirleygilbert!
just wanna do my part for the primary kids (& parents of course) with whatever open-source information I can lay my hands on. Thank God that 14 of my cousins have already completed their PSLE. 4 more to go..haha!!

And yes, my mum is the eldest of her 8 siblings. (ok...too much information here) haha!

[Mum1113]

ADoc:

Which of the following does/do not reflect light?
(1) glass
(2) mirror
(3) opaque cloth
(4) transparent liquid

A: (1) only
B: (3) only
none of the above
(3) & (4)

DS answered this : D . Correct ?

[anneshirleygilbert]

Mum1113:

ADoc:

Which of the following does/do not reflect light?
(1) glass
(2) mirror
(3) opaque cloth
(4) transparent liquid

A: (1) only
B: (3) only
none of the above
(3) & (4)

DS answered this : D . Correct ?

My daughter says the answer is C. We are able to see them because light falls on these objects and they reflect the light into our eyes, thus enabling us to see them. Is she right? :?

[ADoc]

anneshirleygilbert:

Mum1113:

[quote=\"ADoc\"]
Which of the following does/do not reflect light?
(1) glass
(2) mirror
(3) opaque cloth
(4) transparent liquid

A: (1) only
B: (3) only
none of the above
(3) & (4)

DS answered this : D . Correct ?

My daughter says the answer is C. We are able to see them because light falls on these objects and they reflect the light into our eyes, thus enabling us to see them. Is she right? :?[/quote]We

Hi anne, mum1113!
the answer should be C.
In the context of primary syllabus, the key concept would be \"as long as an object can be seen, it means it reflect light\". Just an additional piece of info: in our usual daily lives, we would expect to \"see through\" (clear) glass & transparent liquid, especially when we start to recall hilarious (& even real-life sometimes) scenes of movies whereby someone bumps into a glass. That would be \"visually\" true if there aren't any frames (for glass) or containers (for the transparent liquid). Optically, however, a 100% transmission of light (\"invisible\") by any material (let's not talk about our surrounding air, micro-organisms, etc. for example) is unattainable unless there's an absence of structural defects such as voids, cracks, etc.

cheers!

[anneshirleygilbert]

Thank you, ADoc for the added info. From the time I learned language and articulation, I was always taught, \"We see the table, we see the rainbow .....\" Now, in Spore Primary Science, my daughter says, \"Light falls on the objects and then bounces off into our eyes, causing us to see.\" This makes so much sense! and what a reverse in the direction of perspective! Perhaps, someday, we should start teaching children this concept from the very beginning of their lives. That should erase a lot of confusion, don't you think? Thanks, ADoc for that question.

[Mum1113]

anneshirleygilbert:

Thank you, ADoc for the added info. From the time I learned language and articulation, I was always taught, \"We see the table, we see the rainbow .....\" Now, in Spore Primary Science, my daughter says, \"Light falls on the objects and then bounces off into our eyes, causing us to see.\" This makes so much sense! and what a reverse in the direction of perspective! Perhaps, someday, we should start teaching children this concept from the very beginning of their lives. That should erase a lot of confusion, don't you think? Thanks, ADoc for that question.

Many tks to ADoc and anneshirleygilbert

[wkong]

Thanks ADoc for the explanation of the questions I posted earlier on.


I have another question that I need advice:

The answer is (3) or (4)?


http://postimage.org/image/1sz47y62s/

[wkong]

This question is abit tricky, should it be (2) or (3)? Which is the keyword that gives the hint of the answer?



http://postimage.org/image/w313pnlw/

[ADoc]

anneshirleygilbert:

Thank you, ADoc for the added info. From the time I learned language and articulation, I was always taught, \"We see the table, we see the rainbow .....\" Now, in Spore Primary Science, my daughter says, \"Light falls on the objects and then bounces off into our eyes, causing us to see.\" This makes so much sense! and what a reverse in the direction of perspective! Perhaps, someday, we should start teaching children this concept from the very beginning of their lives. That should erase a lot of confusion, don't you think? Thanks, ADoc for that question.

haha! Absolutely!
Then again, as math & science become our kids' lingua franca, that's also when they begin to shed the child in them (which is one of most valuable gifts that any can have)...what a pity!

(kids shouting in the background) \"That's life cycle for you!\"

[ADoc]

wkong:

Thanks ADoc for the explanation of the questions I posted earlier on.


I have another question that I need advice:

The answer is (3) or (4)?


http://postimage.org/image/1sz47y62s/

Hi! The answer would be (2). And this sort of question is always highly contentious in the sense that students can be as creative as they can and think of many possible combination of energy conversions.

Let's take it as option (1) is definitely out. The rest of the three are just as equally valid. The debate is really what goes on in the middle.
The way I guide my students is: the final (or desired outcome) energy must always be stated, whereas the start can sometimes be skipped to the next energy conversion depending on the question. What goes on in between must always contain the main components of the equipment.

For this question, we have no problem see that the desired outcome is the sound produced by the bell, hence sound energy. The start can be potential (chemical) or electrical energy. The main components are the solenoid (magnetic energy) ---> attracting the iron bar and hammer as a single component (kinetic energy).

option (3) misses out on the important aspect of a bell which is the magnetic energy.

option (4) misses out the important action of the bell which is essentially the movement (kinetic) that causes the hammer to strike the bell.

Of course, we can always list heat energy as well, but that's unnecessary in this case as it's not the desired outcome, unless the question explicitly states so.

If this wasn't an MCQ question, I would list the energy conversion diagram as:

chemical potential --> electrical --> magnetic ---> kinetic ---> sound

any other views from other forum-ers?
cheers!