Q&A - PSLE Science

[corneyAmber]

Totally agree with tianzhu.


Btw, some of the Science content today are concepts learnt only in secondary school in the past…eg. potential and kinetic energy was covered only in sec. I suppose with Internet age and alot of enrichment centres with holiday programmes where information is readily available, they are expected to read & know much more than in the past. No right or wrong but learning is now generally accelerated and many of my friends with P5/P6 kids always scream the lack of time to do anything else other than prepare for PSLE. Just an obervation only.

[Dharma]

tianzhu:

Hi

Thank you for your active participation.

First, we have to accept the fact that we are parents, not trained educators. For varied reasons, we may be more involved in our children’ studies than others.

Our knowledge in Primary Science is gained through reading up from our kids’ books .We have to agree Science questions nowadays are so much different from our times. Many a times, I am floored by them.Primary Science is fascinating and challenging. Kids have to use the right concepts and apply them appropriately to answer the questions. And, these have to done in one or two lines. You have to be stingy with words, using the right key words and phrases. Given the class sizes of about 40 active kids, it’s not easy for a school teacher to reach out to them. Therefore, particularly for those without tuition, parental guidance is important.

Let’s take this thread as a learning platform where parents and students exchange their ideas freely and learn from one another. We may not always come up with the so called model answers, but may offer some tips where another can tap to expand the ideas further. Along the way, mistakes will be made, but at least, we know that they are made with good intentions. We just want our kids to grow to their fullest potentials.

Tianzhu,

You couldn't have been more correct!!!

[ChiefKiasu]

tianzhu:

...First, we have to accept the fact that we are parents, not trained educators. For varied reasons, we may be more involved in our children’ studies than others...

While not all parents are trained as educators, I would trust a group of well-meaning and educated parents with the web resources at their fingertips more than a Primary school teacher who only wants to teach and test material from the school's text. Yes, we all make mistakes, but the web and this Forum is so open that our mistakes will be discovered and corrected by other parents who may happen to be more familiar with the topic. Our combined responses will not only produce the best answer, but also highlight the common pitfalls that our children will probably encounter (since we encountered them ourselves!).

For this reason, I'm thankful for Tianzhu's earnest and untiring postings of the key problems he encounter while going teaching his children, and for the participation of members such as Dharma/Dharmaratnam and ks2me who share their thoughts on the problems.

[tianzhu]

Thank you for your help.

Please click at link and refer to MCQ Q14 on pg9.
( http://www.wendykoh.com/08/primary6-methodistsa1-science.pdf )

The given answer is (2).
However, from i-science P4, pg 67, we learned that mudskippers can also breathe through their skins by keeping it damp.They can also breathe by holding water in their mouths and gill chambers.

Do you know of any list showing how animals breathe?Is this answer correct?

[tianzhu]

Thank you for your help.

From experience, we know that milk flowed slowly out of a tin when there is one hole. We usually make one diagonally opposite to speed up the flow.
What are the relevant PSLE Science concepts to be applied in this question?
http://farm4.static.flickr.com/3032/3471323833_d5d51de0c9_o.jpg\">

[tweet]

tianzhu:

Thank you for your help.

From experience, we know that milk flowed slowly out of a tin when there is one hole. We usually make one diagonally opposite to speed up the flow.
What are the relevant PSLE Science concepts to be applied in this question?
http://farm4.static.flickr.com/3032/3471323833_d5d51de0c9_o.jpg\">

Hi Tianzhu

This is about air occupies space.Making another hole is to allow air to enter and occupies the empty space in the tin while the milk flows out from the other hole.The air will replace the milk till the milk in the tin is emptied.

Rgds
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[ChiefKiasu]

tianzhu:

Thank you for your help.

From experience, we know that milk flowed slowly out of a tin when there is one hole. We usually make one diagonally opposite to speed up the flow.
What are the relevant PSLE Science concepts to be applied in this question?

This is a question about atmospheric pressure. The question can come in various forms, ranging from the trick where a piece of cardboard covering the mouth of a completely water-filled glass can hold its place even when the glass is fully inverted, to versions such as this question.

The pressure on us being at the bottom of the \"mountain\" of earth's atmospheric gases is immense, and we don't feel it only because of our internal fluid pressures which balances out the external force.

Atmospheric pressure is pushing against the downward force exerted by weight of the condensed milk in the can. As the hole is small, the amount of force presented by the weight of fluid (milk) at the hole is small compared to that of the atmospheric pressure acting against it, so the milk flow is slow.

If we puncture a hole at the other (top) end of the can, the atmospheric pressure at the top of the can is now much higher than the air or fluid (milk) pressure previously in the enclosed can, so the milk will flow much faster.

[tianzhu]

Dharmaratnam:

Dear ksmama,
The 1st sentence talked about 2 paper bags. The 2nd sentence mentioned that there was a thick plastic bag that was the same size and shape of the paper bag.
The picture however, shows a plastic bag and another with paper bag inside the plastic bag.

Hi, ksmama and Dharma

Thank you for your responses. I’ve done some reading and found that the process when water enters the cells is called osmosis. I remembered reading about it when I was doing my Physical Science in secondary schooldays. So this is just for additional information.
http://www.wisegeek.com/what-are-some-differences-between-plant-and-animal-cells.htm
http://www.purchon.com/biology/osmosis.htm#osmoplant

Going back to the question again, part (b) gives a clue that this question is from the topic Cells in P5.Plant cell has an additional cell wall (fully permeable) as well as a semi-permeable cell membrane. Some books called it selectively permeable. Animal cell has only a cell membrane.
When immersed in pure water, the cell membrane of the animal cell swells up and bursts when it cannot stand the strain anymore. The cell wall of the plant cell is much stronger than the cell membrane and prevents the cell membrane from bursting.

Perhaps, we can compare the plastic bag to that of a cell wall and the paper bag to the cell membrane. Hope this is of some help.

[tianzhu]

ChiefKiasu:

This is a question about atmospheric pressure.

Hi
Talking about atmospheric pressure, I like to share some videos which I chanced upon while surfing.
http://www.videojug.com/film/how-to-suck-an-egg-into-a-bottle
http://www.youtube.com/watch?v=zl657tCCudw
http://www.youtube.com/watch?v=tlQ3qj4eL9s&feature=related

[mathsparks]

Just wondering if anyone knows the answers provided in wendykoh’s/other top schools papers bought in neighbourhood stalls are accurate.


Any idea if the answer keys are from the schools? I seem to find a few that don’t make sense.