Q&A - P4 Science

[smartmummy]

Bookwrappers:

Hi experts here. Would like to ask, in p4 sci. They learn light travels in straight line. Many experiments in guide books confirm this in various experiments.


However just curious, if light travels in straight lines, does it mean that when we light a torch in a dark room, the ray of light only shines in one direction so only the part that is shone will be seen. In that case, when we switch on the center ceiling light in a room, we should only see things right under the light and not at a corner?

My thinking as follows,Diameter of torchlight much smaller than ceiling light. Sun's diameter sooooo big that's why we all can see at day time.

[Nebbermind]

Bookwrappers:

Hi experts here. Would like to ask, in p4 sci. They learn light travels in straight line. Many experiments in guide books confirm this in various experiments.


However just curious, if light travels in straight lines, does it mean that when we light a torch in a dark room, the ray of light only shines in one direction so only the part that is shone will be seen. In that case, when we switch on the center ceiling light in a room, we should only see things right under the light and not at a corner?

Firstly, the light source does not produce a single beam, and also a certain amt of light will lo be reflected by the various surfaces in the room.

If u gave a single beam such a one from a laser pointer, u can't see much with it.

[smartmummy]

Hi all!

I have a doubt.How do u answer for (b).Usually the qn like \"what is the property of light....?\", I always see the answer is \"light travels in straight line\".My son asking why is not \" light can be reflected\"
http://i50.tinypic.com/2evw6px.jpg\">

[Jamesbond]

smartmummy:

Hi all!

I have a doubt.How do u answer for (b).Usually the qn like \"what is the property of light....?\", I always see the answer is \"light travels in straight line\".My son asking why is not \" light can be reflected\"
http://i50.tinypic.com/2evw6px.jpg\">

We can say mirror reflects the light which travels in st lines. That wud be apt for such questions.

[chloecube]

sleepyqueen:

tayobus:

http://i49.tinypic.com/2aont0.jpg\">


Dear All,
My child is doing the past year paper and when come to the above question, he said not his level topic and he found out from the PSLE Science guide book it is upper block topic. Can anyone advise does your P4 child learnt the above? How do your child answer the above? By the way, this is taken from Nan Hua Pri SA2 2011 paper.

:thankyou:

Hi all,
I think this question not necessary be the upper level one as the kid are taught in p3 that flower will change colour if dip in coloured water. Now the stem is cut into 2 and soaked in different coloured solution. P3 the kids are also taught that roots take in water and the stem transport it to the other parts of the leaves.

my son just did this same paper ytd, it is a pretty common question for P4.
my son's answer was \" the flower turned purple (red and blue mixed together) but it was wrong as the correct answer is, \"half of the flower turns red and the other half blue. \"

[atutor2001]

Jamesbond:

smartmummy:

Hi all!

I have a doubt.How do u answer for (b).Usually the qn like \"what is the property of light....?\", I always see the answer is \"light travels in straight line\".My son asking why is not \" light can be reflected\"

We can say mirror reflects the light which travels in st lines. That wud be apt for such questions.

Hi smartmummy
You have actually asked the \"correct question\". This is an example of \"indirect way\" of questioning. Instead of reading the question as \"Explain why Peter can see Ali\", the student needs to be trained to rephrase the question as \"Explain using the properties of light, why Peter can see Ali.

Jamesbond's answer will suffice for P4 or if it is a (1) mark question at P5 or 6. However, if it is a (2) mark question at P5 or 6, it is safer to elaborate on how the said properties will help Peter to see Ali. So by some modification to Jamesbond's answer, we get

\"Peter can see Ali because light travels in a straight line and is reflected by Ali to the 2 mirrors and then to Peter's eyes.\"

[Jamesbond]

atutor2001:

Jamesbond:

[quote=\"smartmummy\"]Hi all!

I have a doubt.How do u answer for (b).Usually the qn like \"what is the property of light....?\", I always see the answer is \"light travels in straight line\".My son asking why is not \" light can be reflected\"

We can say mirror reflects the light which travels in st lines. That wud be apt for such questions.

Hi smartmummy
You have actually asked the \"correct question\". This is an example of \"indirect way\" of questioning. Instead of reading the question as \"Explain why Peter can see Ali\", the student needs to be trained to rephrase the question as \"Explain using the properties of light, why Peter can see Ali.

Jamesbond's answer will suffice for P4 or if it is a (1) mark question at P5 or 6. However, if it is a (2) mark question at P5 or 6, it is safer to elaborate on how the said properties will help Peter to see Ali. So by some modification to Jamesbond's answer, we get

\"Peter can see Ali because light travels in a straight line and is reflected by Ali to the 2 mirrors and then to Peter's eyes.\"[/quote]Yes...If it is a 2 mark question even for P4 I would agree your answer should be given....

[atutor2001]

chloecube:

http://i49.tinypic.com/2aont0.jpg\">

my son just did this same paper ytd, it is a pretty common question for P4.
my son's answer was \" the flower turned purple (red and blue mixed together) but it was wrong as the correct answer is, \"half of the flower turns red and the other half blue. \"

I think the purpose of this question is to test the understanding that the xylems are individual tubes and water flowing through one tube will not mix with water in other tubes, which is why the red and blue solution will not mix to form purple solution.

As for the given answer, my only uneasiness is with the word \"half\". Science is very specific so if we say half, than exactly \"HALF\" of the flower must be red and the other half blue. We know it is not possible for this to happen so it may be good to train the students to avoid such words if it is probably not exactly true. I would prefer to use \"part of the flower is red and part of it is blue\"

[jedamum]

Atutor,

My boy answer part blue part red,my concern is will it be implied that there are some parts remain white?

[atutor2001]

jedamum:

Atutor,

My boy answer part blue part red,my concern is will it be implied that there are some parts remain white?

Yes part of the flower will remain white because the xylems will not cover the entire surface area of the petals. I used to teach my children to write this way :

Part of the flower will have red strips while other part will have blue strips. The red strips and blue strips are caused by red solution and blue solution flowing in the xylems respectively.