Tutor Niedino: Pri Science Questions and Concepts

[anneshirleygilbert]

Hello Everyone,


I need some help in crafting a comprehensive answer to this question:
"What is a control set-up in an experiment? and what is its purpose?"

I’ve not read anything from Niedino for a long time. Would really appreciate her input.

Sincerely,
Anne

[thensingsmysoul]

anneshirleygilbert:

Hello Everyone,


I need some help in crafting a comprehensive answer to this question:
\"What is a control set-up in an experiment? and what is its purpose?\"

I've not read anything from Niedino for a long time. Would really appreciate her input.

Sincerely,
Anne

Control set-up in an experiment has the exact same conditions as the experimental setups except for the tested variable( changed variable).

Purpose:
To ensure that any changes/difference in the (variable changed/result of the experiment) is due only to the (changed variable) and not due to other variables/factors.

E.g.
Aim of experiment: To find out if the presence of wind affects the rate of evaporation.
CV: presence of wind
Variable measured: amount of water left in a container at the end of the experiment

Control set-up:
Container left in a location without exposure to wind

Purpose of control set-up:
To ensure that any changes in the amount of water left in the container at the end of the experiment(or \"any difference in the rate of evaporation\") is only due to the presence of wind and not due to other variables.

Hope this helps.

Regards,
KC

[Niedino]

anneshirleygilbert:

Hello Everyone,


I need some help in crafting a comprehensive answer to this question:
\"What is a control set-up in an experiment? and what is its purpose?\"

I've not read anything from Niedino for a long time. Would really appreciate her input.

Sincerely,
Anne

Hi Anne,

My apologies for the really late response, I've been pretty busy with my work and with the shifting of the forum topics, I got lost initially. I'll try to visit the forum as much as possible. Actually KC provided a very detailed explanation. :goodpost: In the primary school syllabus, a control is basically a setup that has the exact same conditions as the experimental setup, except for the change in one variable, the independent variable or the cause. This is to ensure that the experiment's findings are reliable and due to the independent variable or in other words, the effect is due to the cause.

Do note, many students often write that the reason for having a control is to have a fair test. This is a misconception. Having only one variable changed is to have a fair test. Having a control setup is to ensure that your results are reliable. Repeating the experiment is to reduce the chance of human error.

Hope it helps!

[Niedino]

Dear Parents


I have just posted some tips on my blog on how to answer Section B questions. Unfortunately, its not been posted on the main page yet. Here's the link. http://www.kiasuparents.com/kiasu/conte ... -questions

Here's my tutor profile on kiasuparents which has been verified by ChiefKiasu. http://www.kiasuparents.com/kiasu/conte ... ng-niedino

I have helped many pupils to improve in their Science during this year's PSLE.

I have some classes opening in 2012, if you and other parents are interested, you may want to drop me an email at [email protected] or pm me for my contact details.

You may also wish to join my mailing list (which I'll start once there are enough interested parents).

Hope it helps

Niedino

[Pebblesrock]

Why does the electrostatic force of attraction decreases when the size of the ion decreases whereas when the molecules get bigger in a covalent compound, the intermolecular force of attraction increases? It sounds contradicting.

[petals73]

Hi I would like to find out more on the marking scheme for PSLE science.


My P4 DD had these type of questions during her SA1 and CA2 exams. One of them were:
They were given 7 things and were told to group them into "good" and "bad" conductors of heat. The correct answer will be 3 items will fall into "good" and 4 items will fall into "bad". She’s got 5/7 correct but no marks were awarded at all. So she lost the entire 2 marks. When I checked with her teacher, she said the school were following the marking scheme of PSLE.

Please advise if this is true. Many thanks

[Niedino]

Goodluck8:

Need help


When DDT is used, will the conentration of the DDT level in the food consumers be higher or lower? The school teacher explained that it will be lower as DDT will be expelled from the animals through their faeces. DDt will only kill the insects but not the animals

But i read quite a number of articles and seem it is not true. Can you help me?thanks

Second question
which requires more force : pulling the load up a inclined plane or lifting the same load vertically up? The teacher answer is pulling it up a inclined plane because it need to overcome gravity and frictional force but lifting it up requires to overcome the gravity only.????

Dear Goodluck,

Apologies for the late reply. Its really been busy. For the first question, I believe that it depends on the amount of DDT. Without the question, I am unable to comment more.

As for the second question, the accepted answer is usually the inclined plane as 2 forces need to be overcome instead of 1. However, if there is a way to reduce the frictional force, e.g. adding wheels, or adding lubricants, then it may be different. I can see where the child must be thinking, if I cannot lift this, perhaps I can push it along the ground. But pushing it up a ramp and pushing it along a flat ground requires a different amount of force.

Hope it helps!

[Nebbermind]

Goodluck, is the force qyestion for p6 and is it from school or enrichment centre?

[mwchua]

hi Niedino, dropped you a pm…just wondering if you have have chance to read through yet? thanks.

[phtthp]

Hi niedino,

I had sent u a pm. Appreciate if u can respond. Tq