Q&A - PSLE Science

[atutor2001]

There is a problem of "incomplete" teaching in primary science concept and understanding because of the level of difficulty. Therefore, the science text needs to highlight at the end of every topic that what they have learnt are only the basics and there are many other aspects (perhaps giving some examples) so that children are more aware that science is much more than what they have learnt.


The real issue is that many science teachers have no love for science and simply give absolute answers like yes and no based on the given answer keys. The scenario of "maybe" is hardly used to stimulate the mind of the students.

[anneshirleygilbert]

tianzhu:

Hi anneshirleygilbert


In PSLE science, I think it is good enough to know that the presence of impurities (salt) increases the boiling point and reduces the freezing (melting) point of water.

This link may help to address your query on the effect of salt on freezing/melting point of water.

http://www.worsleyschool.net/science/files/saltandfreezing/ofwater.html

Best wishes

Thank you, tianzhu. The link is really an interesting read... and so helpful too. You are very resourceful. I read in the past posts that you also had a son who did his PSLE in 2009/2010? How diligent you were for his sake. I hope to do the same for my daughter. Thanks for all your help.

[ChiefKiasu]

atutor2001:

wkong:

========================
The answer will have to be 3. There is chemical potential energy in the dry cells which will be converted to electrical energy when the circuit is closed. The striker will move as a result of kinetic energy and then sound and heat.

Number 3 best fit this conversion order.

There is no such thing as magnetic energy. Magnetism is a force.
========================

Though I agree with the teacher's answer, I disagree with \"There is no such thing as magnetic energy\". There must be Energy before a force can be produced. If there is no magnetic energy, where does magnetic force come from? It is along similar concept that gravity / gravitation force is the result of Gravitational Potential Energy. Maybe the teacher felt that it should be called magnetic potential energy.

Well, if we agree that there is such a thing as \"magnetic energy\", then wouldn't (2) be the most suitable answer ?

Herein lies the problem with Primary school science. The examiners are focusing too much on the detailed classification and nuances of the subjects that they lose sight of the whole picture. The simplest explanation of the bell example would be the conversion of potential energy stored in the cells being converted to kinetic energy which culminates in the generation of sound waves/energy. By trying to break it up into more discrete parts to make the question more \"challenging\", the examiners run the risk of slapping themselves. The full answer should be:

Potential energy (chemicals in cells)
-> Electrical energy (flow of electrons generated by electrochemical reactions in cell going from -ve to +ve terminals)
-> Electromagnetic field energy (created by electrons flowing around the electrical coils, creating a magnetic force that affects particles in the field)
-> Kinetic energy (as the magnetic force attracts the metal plate towards the coil)
-> Sound energy (as the clanger hits the bell)

This is why I always have disagreement with Science teachers

[atutor2001]

ChiefKiasu:

Well, if we agree that there is such a thing as \"magnetic energy\", then wouldn't (2) be the most suitable answer ?

Aiya Chief, I agree with the answer (3) because Pri kids didn't learn Magnetic energy ma. So within their limited knowledge, they are expect to pick (3) as the answer lah.

Unfortunately by agreeing with (3) without qualification, I give the impression that (2) is wrong. No no that is not my thought. My apology for misleading the readers. Next time I will be more careful and complete. However, I was really upset when the teacher replied in writing somemore that there is no such thing as magnetic energy. Totally wrong concept. You very gentleman, only have disagreement with science teachers. Last time I always quarrel with them until my kids barred me from going to see their teachers. :lol:

[wkong]

atutor2001:

You very gentleman, only have disagreement with science teachers. Last time I always quarrel with them until my kids barred me from going to see their teachers. :lol:

Hi atutor,

Your kids are so cute.. barred you from seeing teachers. My DS barred me from asking teachers any questions during P6 Dialogue session as well as during Science workshop too.

Of course, during the Science workshop, I see parents argue the answer with Science teacher, but.. winner is always (you know lah).

[atutor2001]

wkong:

Hi atutor,

Your kids are so cute.. barred you from seeing teachers. My DS barred me from asking teachers any questions during P6 Dialogue session as well as during Science workshop too.

Of course, during the Science workshop, I see parents argue the answer with Science teacher, but.. winner is always (you know lah).

Hi wkong

So happy to find someone in the same boat and I am not alone. :celebrate:

[Flipper123]

Could someone explain to me why when germination,seeds need warmth.Does this have anything related to winter? :?

[atutor2001]

Flipper123:

Could someone explain to me why when germination,seeds need warmth.Does this have anything related to winter? :?

Last time, if my kid asked me this question, my answer will be \"ask god tonight when you are sleeping\" :lol:

I also don't know the answer but can only guess using logical thinking that energy (heat/warmth) is usually needed to start or speed up most chemical reactions. Germination in a way is a form of chemical reaction happening inside the cells of the seed.

I stand corrected. Maybe you can google for the answer and teach us. OK?

[ADoc]

atutor2001:

Flipper123:

Could someone explain to me why when germination,seeds need warmth.Does this have anything related to winter? :?

Last time, if my kid asked me this question, my answer will be \"ask god tonight when you are sleeping\" :lol:

I also don't know the answer but can only guess using logical thinking that energy (heat/warmth) is usually needed to start or speed up most chemical reactions. Germination in a way is a form of chemical reaction happening inside the cells of the seed.

I stand corrected. Maybe you can google for the answer and teach us. OK?

Haha! You are humorous! And yes God definitely has all the answers! if only I...

...\"stand corrected\"? echoing the father of someone...haha!

Anyway don't be so bad lah...let's try to answer his/her query.

[ADoc]

Flipper123:

Could someone explain to me why when germination,seeds need warmth.Does this have anything related to winter? :?

hi flipper!
Germination has to do with cellular metabolism as what atutor has pointed out. And the conditions (such as air, water, warmth & even light for some types of plants) have to be \"just right\" in order to ignite this metabolic process. [by the way, pls ignore light as primary science syllabus does not include light for germination]

Think of a (embryonic) seed (which means it has the potential to grow as opposed to a \"dead\" or empty seed which will not grow even if the conditions are favorable) as a super smart hibernating machine. And think of the KEY to this machine as the right amount of air (oxygen), water, & \"warmth\". Under suitable conditions, you will be able to unlock this machine with this key. In other words, the seed will \"decide\" to come out of its hibernation by activating its metabolic process.

Warmth is one of the conditions for activating this metabolic process.

[This part not required in PSLE syllabus]
Do understand that warmth is relative, and to different species of seeds warmth can be anything from above or below room temperature (during each of the four seasons) or even below zero deg.

I could have a body temperature of say 30 deg, so anything above 30 will be considered warmth to me. Similarly, at say 4 deg during winter, anything above 4 deg will be considered warmth. So you see, warmth is relative depending on your reference point.

The more accurate term would be temperature. While some seeds require \"warmth\" at about 20-25 deg maybe, other seeds will only germinate during winter when the temperature is much lower, i.e. even if it's 20-25 deg ( very \"warmth\"), these sort of \"winter\" seeds will not germinate.

hope this makes sense to you..cheers!