Q&A - PSLE Science

[atutor2001]

Alarmchain:

Thank you so much to both Charsen and atutor, appreciate your inputs!


To atutor:
I finally understand the reasoning of the teacher, thank you!

However, as friction generates heat, which is how my daughter and I had explained in the answer in my original post, wouldn't that be similar to your last sentence of \"Therefore, the total amount of heat gained by the lizard is much lesser than the snake and it can move a longer distance over the hot sand compared to the snake.\", since the snake would have gained more heat generated by friction as well?


My thought :
I have simplified the last sentence just for easier understanding at Pr level. The reason for the snake or the lizard to stop moving and seek for shade from the sun is when the heat gained at the part of the body in contact with the hot sand is so high that they will get burnt.

The heat gained through friction is negligible compared to that by conduction from the hot sand. Therefore, it is a minor factor and will not be accepted as an answer.

If we had explained it as friction being an opposing force and therefore it results in a shorter distance travelled, I will then agree that it may not have fully answered the context of this question.

Appreciate your thoughts on this.

Thanks!

[cimman]

Alarmchain, it is very important to answer in context of the question.

Most students do not understand the essence of the question.
For example, what is the difference between a Red Ferrari and a white Mercedes Benz ?
one can say, the colors are different. However, this would be a wrong answer.
The essence of these 2 cars, is that one is a sports car and the other is a sedan. So while technically, the 2 cars have different colors, the objectives of the 2 cars are very different.
In your case of the lizard and the snake, while there is friction involved, ask yourself this question, if it is night time in the dessert, would the lizard and the snake covered the same distance ? yes, they would, despite the snake having to overcome the greater frictional force. The essence of the question is that it happened in the dessert in the day time. The dessert is known for 2 main things, extreme heat and dryness. We can discard lack of water here, since nothing in the question links to that. You have to link the answer back to the extreme heat in the dessert. Link your answer to the essence of the question, do not look for superficial differences, though it may be technically correct, but it will be marked wrong.

[kitty2]

charsen:

kitty2:

Series or parallel circuit is brighter?Circuit with series battery is bright or with parallel battery?Circuit with series bulb is brighter or with parallel bulb?


Please help as my nephew is very confused with the above.

Thanks

It depends on the arrangement of batteries or the arrangement of bulbs of the circuit.I can tell what the brightness of the bulb is when you say the arrangement of batteries is in series or parallel or the arrangement of bulbs is in series or parallel.
Cheers

Please let me know your answers for the above.Thanks

[Sun_2010]

cimman:

Alarmchain, it is very important to answer in context of the question.

Most students do not understand the essence of the question.
For example, what is the difference between a Red Ferrari and a white Mercedes Benz ?
one can say, the colors are different. However, this would be a wrong answer.
The essence of these 2 cars, is that one is a sports car and the other is a sedan. So while technically, the 2 cars have different colors, the objectives of the 2 cars are very different.
In your case of the lizard and the snake, while there is friction involved, ask yourself this question, if it is night time in the dessert, would the lizard and the snake covered the same distance ? yes, they would, despite the snake having to overcome the greater frictional force. The essence of the question is that it happened in the dessert in the day time. The dessert is known for 2 main things, extreme heat and dryness. We can discard lack of water here, since nothing in the question links to that. You have to link the answer back to the extreme heat in the dessert. Link your answer to the essence of the question, do not look for superficial differences, though it may be technically correct, but it will be marked wrong.

Wonderful explanation cinman. Thanks.

[Alarmchain]

Thank you so much to both atutor and cimman. Really appreciate you guys taking the time to fully elaborate the minor nuances that makes the difference between a right and wrong answer.


I do get the point about superficial and main reasons behind an answer and about answers that fulfil the context of a question.

However, I am indeed very worried about such methods of examining science, especially to kids 12/13 years of age. Unless this is the type of question that separates an A from an A* student, it would indeed not only confuse most kids (as well as parents and teachers, I might add!), it may actually turn them off!

Much as heat from friction is not the main reason and is only technically correct, I do believe that if a child is able to reason it that way, it should not be marked wrong. Unless the reasoning was way off, or concepts were wrongly interpreted, we should be teaching our children this reasoning technique and not give them the impression that there is only 1 answer. Yes, I do agree that in this instance, the main reasoning should be the intense heat from the hot desert sand. However, I wonder if in the actual exam papers, the words \"hot sand\" was in bold to capture the child's attention. Even so, under exam conditions, how does one expect a normal 12 year old to be able to realise that and also be able to phrase the answer in the way we did! Indeed, I may even argue that it is precisely because of the hot sand that the minute heat from friction becomes an even more important factor, versus when the 2 reptiles were moving in the cool of the night.

This question would have been an ideal one for the school science workbooks, which I am sure many will agree, is grossly lacking in such application questions (and yet they expect our children to tackle such questions during exams, to such minute details too!). It would indeed generate good discussions in class on how concepts are applied in various ways. But under exam conditions??? (unless it is one of the few that separates the A from the A*)

It is such narrow interpretations of answers and marking schemes that have now resulted in science being taught in a very narrow manner in schools, unfortunately (we all must know of the keywords way of teaching science today). If science for 12 year olds is about exciting the kids to explore things around them, I wonder if stressing NARROWLY on being scientifically and technically correct answers is the right way to go. We are not talking about being way off, of course.

My apologies for straying off. Just wonder if there are parents out there who feel the same way.

Once again, my gratitude to both for your inputs. At least, I can now \"correctly\" explain this question to my daughter.

Cheers!

[atutor2001]

Hi Alarmchain


In my opinion, such questions are to "prevent" students from getting full mark. Generally, such type of questions will add up to only about 5 marks of the whole paper. So even if they get it wrong, A* is still attainable.

[Alarmchain]

Ha ha ha … good to know!


But I guess it is the bigger implications on the schools … since they will teach based on the way the subject is assessed … as they have KPIs to meet.

And we will have another generation of young who only knows 1 answer … and not the reasoning techniques behind it.

Cheers!

[elkniwt]

Hi Alarmchain,


My dd also did this qn in the PSLE booklet and her answer is almost the same your dd’s answer and she got it correct. Hmm… honestly I don’t really understand why your dd’s teacher mark her wrong. (I guess I have a lot to learn …)

My dd’s ans is : There is lesser friction between the lizard and the sand and thus it can move a longer distance.

Regards.

[Alarmchain]

Thanks elkniwt.


My daughter is taught by the science HOD in her school and the class was told that for PSLE that year, friction as an answer was marked as wrong for this question!

Which is what worries me most. Teachers are PSLE exam markers. We are told that should the markers get answers which are plausible, they will raise it to the supervisors, who will discuss and then decide if such answers are to be included in their marking schemes.

Honestly, how many teachers will, upon marking, realise and then raise this question for further discussions? (You are already the 2nd person to say that the teachers accepted the child’s answer of friction during their practice / revision.)

It is not the marks that matters, since every child in that PSLE, with friction as the answer, would probably be marked wrong for that question, I suppose.

But it is the implication on these teachers, who will then go back to school and teach science thereafter. Teachers are generally a caring lot and would want our children to do well. I can imagine them, having experienced how narrow SEAB can be in what constitutes a correct answer, returning to schools and teaching our children in the very same narrow manner, or even narrower! Is this preparing our children with 21st Century skills?

Pardon my ranting, its just that this has been the way with science for so long, it is getting very frustrating. Not just for the parents, but I’m sure for the teachers and most importantly, our children as well.

Thanks anyway, appreciate your sharing.

[Winx5015]

Hi, anyone know the answer for the following questions? Thanks!

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