Tutor Niedino: Pri Science Questions and Concepts
-
atutor2001:
\"PSLE questions are OK\" meaning their questions are not ambiguous but can be very tricky. Only kids who are good in English will do well as they can understand the \"limits\" and requirements set in the question - so they don't have to waste time putting in the unnecessary extras.starlight1968sg:
[quote=\"atutor2001\"]Problems with the questions usually happen only in school papers and I think PSLE questions are OK.
I am unsure about this part. If kids can't do well in the school papers, can they do well in PSLE?
For others who are trying to match questions to answers from what they have learnt in the past, they would not appreciate the \"limits\" set in the questions and continue to try their luck by including whatever they can remember in their answer, not knowing that certain part of \"standard answers\" is no longer relevant because the \"conditions\" set in the question can completely change the required answer. PSLE usually has a few questions that are very tricky and getting to understand the \"limits\" or \"conditions\" is not easy, which is why getting A* for science is tough.[/quote]Hi atutor,
With regards to your earlier post, I would like to provide the flipside of the coin. PSLE questions can be \"ambiguous\" at times, depending on the process skill tested. Every year, after the PSLE, there'll be questions in the papers
Secondly, to the \"inconsistency\" of school papers, I would like to highlight that school papers are set by teachers who are professionals. This are the same professionals who mark the PSLE. Of course, there are papers that are set very well and there are papers that are set inconsistently, and I'm not debating that. We have to understand that school examinations are set to \"prepare\" pupils for the PSLE and hence very often, the setters are trying to set questions that might appear in the PSLE.
I hope not to set a debate on this topic, and close this subject, as the thread is started to focus on helping parents with Science concepts and particularly misconceptions.
So here's another misconception.
Students are often confused between the Primary Science definition of \"Hardness\" and \"Strength\" when they learn about the diversity of materials. Do try and ask your children about whether an object is \"hard\" or \"strong\" when it can withstand scratches or when it can withstand a lot of mass without breaking. Students are also confused with the state of being \"inflexible\" and being \"hard\", due to the prior understandings with the English definitions.
Hope it helps -
atutor2001:
Hi atutor,I think there is another problem with science paper, which is \"inconsistency\" in the expected answer.
If a question is \"Where does paper come from?\", I am sure the answer \"Paper comes from trees\" will suffice. There would be no need to explain how wood is made into paper. Probably the school could argue that the answer to \"how\" is not expected because it is not covered in the syllabus. Nevertheless, I still feel it is good for science question to be phrased in such a manner, consistent with normal English usage, so as to avoid ambiguity.
Problems with the questions usually happen only in school papers and I think PSLE questions are OK. However, because of students exposure to incomplete question and inconsistent expectancy in school, they end up not knowing the limit to the answers required in PSLE.
A typical example is as follows :
An experiment was conducted by pouring equal amount of water into 3 identical funnels containing equal amount of 3 different types of soil. The time taken for 20 cu cm to flow through was recorded. What is the aim of the experiment?
The possible answers that students may have come across are :
1. To find out the the time taken for 20 cu cm of water to flow through each type of soil.
2. To find out the effect of each type of soil on the time taken for 20 cu cm to flow through.
3. To find out how different types of soil will affect the time taken for 20 cu cm of water to flow through.
4. To find out the porosity of each type of soil.
5. To find out which soil is the most porous.
6. To find out which soil retains the most amount of water.
7. To find out which soil would take the longest/shortest time for 20 cu cm of water to flow through.
.....
Our poor kids would be getting wrong / correct for their answers, depending on the school's marking scheme. Anyone can help to explain which is the best answer and which answers are not acceptable and why. Thanks.
Based on my experience, most students will write 1 and 3, which should be correct, as they do not learn porosity at the primary school level. The questions aims to test the pupils on their ability to make conclusions using the information given to them. However, for the very bright ones, who answer 4, 5 and 6, the mark will still be awarded to them as they have answered beyond what is expected of them. As for answer 2, it is not quite right as we're not really testing the effect and as for answer 7, the answer neglects to mention the different types of soil, so its not and ideal answer.
Hope it helps -
Hi Niedino
I understand and appreciate your points and we shall leave it as it is. Incidentally, PSLE questions may not be set by Primary school teachers - just guessing.
Till today, (my kids are now in their teens), but I still do not know the best answer for the question below. I used to tell my poor kids to \"spam\", by combining all the key words into a single answer. Most appreicate it, if you can share your view on the most suitable answer for this question.
Thanks in advance.
[quote]An experiment was conducted by pouring equal amount of water into 3 identical funnels containing equal amount of 3 different types of soil. The time taken for 20 cu cm to flow through was recorded. What is the aim of the experiment?
The possible answers are :
1. To find out the the time taken for 20 cu cm of water to flow through each type of soil.
2. To find out the effect of each type of soil on the time taken for 20 cu cm to flow through.
3. To find out how different types of soil will affect the time taken for 20 cu cm of water to flow through.
4. To find out the porosity of each type of soil.
5. To find out which soil is the most porous.
6. To find out which soil retains the most amount of water.
7. To find out which soil would take the longest/shortest time for 20 cu cm of water to flow through.
.....
[/quote] -
Hi Niedino
Thank you for your answers. Please ignore my earlier posting, didn’t know that you have already replied while I was posting. Thanks again. -
Hi,
I need some help in
http://www.orlesson.org/orp/09Sc/2009-Sc-CA2-Nanyang.pdf Q24
Is the model ans correct in particular option B?
MTIA. -
starlight1968sg:
Hi,Hi,
I need some help in
http://www.orlesson.org/orp/09Sc/2009-Sc-CA2-Nanyang.pdf Q24
Is the model ans correct in particular option B?
MTIA.
The answer should be (3). Option B is correct, as I assume the same substance mentioned here is blood. -
I was going through the topic of heat with my pupils when I realised that many pupils had the misconception that only certain things have heat, and \"cold\" things like ice cubes do not have heat. Here goes ... All things have heat energy, even dry ice and ice cubes. For an ice-cube the amount of heat energy, or degree of hotness can be measured by their temperature, which is 0 degrees celsius. Many pupils misunderstand this and think that cold objects have no heat energy, which is wrong.
So try it with your child and ask whether there's heat energy in an ice-cube. You can then develop this concept with them.
Hope it helps! -
Niedino:
If you say same substance ie blood, then I agreed. But the \"argument\" here is \"substances\" mentioned in the option B.
Hi,starlight1968sg:
Hi,
I need some help in
http://www.orlesson.org/orp/09Sc/2009-Sc-CA2-Nanyang.pdf Q24
Is the model ans correct in particular option B?
MTIA.
The answer should be (3). Option B is correct, as I assume the same substance mentioned here is blood.
OT here:
Thanks for pointing out about heat in all objects.
Another thing to clarify:
(1) blood in the artery (ie leaving the heart) is richer in oxygen but does not mean it has no carbon dioxide.
(2) the air we breathe out contains water vapour and more carbon dioxide but does not mean it has no oxygen.
Am I correct?
MTIA. -
starlight1968sg:
If you say same substance ie blood, then I agreed. But the \"argument\" here is \"substances\" mentioned in the option B.
Hi,Niedino:
[quote=\"starlight1968sg\"]Hi,
I need some help in
http://www.orlesson.org/orp/09Sc/2009-Sc-CA2-Nanyang.pdf Q24
Is the model ans correct in particular option B?
MTIA.
The answer should be (3). Option B is correct, as I assume the same substance mentioned here is blood.
OT here:
Thanks for pointing out about heat in all objects.
Another thing to clarify:
(1) blood in the artery (ie leaving the heart) is richer in oxygen but does not mean it has no carbon dioxide.
(2) the air we breathe out contains water vapour and more carbon dioxide but does not mean it has no oxygen.
Am I correct?
MTIA.[/quote]
Both are absolutely correct but there is something that I want to point out here.....
Arteries are NOT defined by the fact that they carry blood rich in oxygen and veins are NOT classified by the fact they contain large amounts of carbon dioxide.
They are actually classified based on the thickness of their walls. Arteries have thick walls while veins have thin walls. The reason behind is that arteries are blood vessels transporting blood leaving the heart while veins carry blood back to the heart. When the heart pumps, it pumps with great force so the artery walls have to be thick so that they do not burst under the high pressure of the blood flowing. Conversely, blood travelling in the veins have lost most of their momentum thus the vein walls do not have to be thick.
Generally, yes, arteries carry oxygen rich blood while veins transport carbon dioxide rich blood. However, there are 2 exceptions, one in each case. Blood pumped from the heart to the lungs is rich in carbon dioxide but still travels in an artery as it is leaving the heart. On the other hand, blood leaving the lungs to the heart is rich in oxygen but travels in a vein as it is returning to the heart.
Although it is not in the syllabus, I believe it is essential for us to take note of this. I have seen questions when they ask why is the artery wall thick. Of course, the chid's prior knowledge on forces would be sufficient to answer the question but some children, despite getting the right answer, may have second thoughts. Blood leaving the heart to the lungs is rich in carbon dioxide. According to their answer, it should be an artery but then again they think its carbon dioxide rich, a vein. As a result, some children change their answer to another ridiculous one and lose their marks. Having such external knowledge certainly give them an edge over others and they do not start panicking when they see a confusing question.
Hope I have not bored you to death. Please reply if this explanation is confusing. Sometimes my language gets in over my head and makes it difficult to comprehend the scientific concept behind.
-
MOE Hater:
Thanks so much for sharing esp on why arteries have thicker walls!Both are absolutely correct but there is something that I want to point out here.....
Arteries are NOT defined by the fact that they carry blood rich in oxygen and veins are NOT classified by the fact they contain large amounts of carbon dioxide.
They are actually classified based on the thickness of their walls. Arteries have thick walls while veins have thin walls. The reason behind is that arteries are blood vessels transporting blood leaving the heart while veins carry blood back to the heart. When the heart pumps, it pumps with great force so the artery walls have to be thick so that they do not burst under the high pressure of the blood flowing. Conversely, blood travelling in the veins have lost most of their momentum thus the vein walls do not have to be thick.
Generally, yes, arteries carry oxygen rich blood while veins transport carbon dioxide rich blood. However, there are 2 exceptions, one in each case. Blood pumped from the heart to the lungs is rich in carbon dioxide but still travels in an artery as it is leaving the heart. On the other hand, blood leaving the lungs to the heart is rich in oxygen but travels in a vein as it is returning to the heart.
Although it is not in the syllabus, I believe it is essential for us to take note of this. I have seen questions when they ask why is the artery wall thick. Of course, the chid's prior knowledge on forces would be sufficient to answer the question but some children, despite getting the right answer, may have second thoughts. Blood leaving the heart to the lungs is rich in carbon dioxide. According to their answer, it should be an artery but then again they think its carbon dioxide rich, a vein. As a result, some children change their answer to another ridiculous one and lose their marks. Having such external knowledge certainly give them an edge over others and they do not start panicking when they see a confusing question.
Hope I have not bored you to death. Please reply if this explanation is confusing. Sometimes my language gets in over my head and makes it difficult to comprehend the scientific concept behind.
Yes, I know about the pulmonary artery and pulmonary vein.
To make it more precise, arteries carrying blood from the heart to the rest of the body is richer in oxygen except pulmonary artery.
Back to the thickness of artery, vein and capillaries, why capillaries have the thinner walls than veins?
MTIA.
Hello! It looks like you're interested in this conversation, but you don't have an account yet.
Getting fed up of having to scroll through the same posts each visit? When you register for an account, you'll always come back to exactly where you were before, and choose to be notified of new replies (either via email, or push notification). You'll also be able to save bookmarks and upvote posts to show your appreciation to other community members.
With your input, this post could be even better 💗
Register Login