Tutor Niedino: Pri Science Questions and Concepts

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Tutor Niedino: Pri Science Questions and Concepts

Postby Niedino » Tue May 18, 2010 8:51 am

Hi all,

Thought I'll start a thread on this, as I have come across many common science misconceptions that persist among our children today. As a primary school teacher, I often encounter pupils coming in with misconceptions gained from their incomplete understanding of the scientific phenomena around them. :idea: This would in turn affect their understanding when they go to school.

A very common example is the concept of steam. Steam is actually hot water vapour. MISCONCEPTION ALERT! Since we cannot SEE water vapour, we also cannot SEE steam. What we can see from the kettle when water is boiling is the CONDENSATION of steam when it LOSES HEAT to the cooler surrounding air. Many pupils often misunderstand the "hot white mist" to be steam, but they are actually very tiny water droplets (liquid form) rather than steam.

I'll try to maintain a thread on common Science questions, concepts and misconceptions, and how we can guide our children to understand these concepts. Do chip in with your child's questions and misconceptions or misunderstandings as well, and perhaps we can collate them all into a useful piece of information for all parents. :D

Niedino
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Postby Eddow » Tue May 18, 2010 8:58 am

Thanks alot for starting this thread. Yes. my son at times will also misconcept abt the steam too.. Will post questions if I come across.
I think it's a great way to share and be corrected..
^_^

Eddow
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Re: Pri Science Questions, Concepts and Misconceptions

Postby tianzhu » Tue May 18, 2010 10:46 am

Niedino wrote:Hi all,

Thought I'll start a thread on this, as I have come across many common science misconceptions that persist among our children today. As a primary school teacher, I often encounter pupils coming in with misconceptions gained from their incomplete understanding of the scientific phenomena around them. :idea: This would in turn affect their understanding when they go to school.

A very common example is the concept of steam. Steam is actually hot water vapour. MISCONCEPTION ALERT! Since we cannot SEE water vapour, we also cannot SEE steam. What we can see from the kettle when water is boiling is the CONDENSATION of steam when it LOSES HEAT to the cooler surrounding air. Many pupils often misunderstand the "hot white mist" to be steam, but they are actually very tiny water droplets (liquid form) rather than steam.

I'll try to maintain a thread on common Science questions, concepts and misconceptions, and how we can guide our children to understand these concepts. Do chip in with your child's questions and misconceptions or misunderstandings as well, and perhaps we can collate them all into a useful piece of information for all parents. :D


Hi

Great, finally we’ve a trained educator who is helping out in science in KSP. Well. I am going to take this opportunity to clear up some misconception concerning bubbles in boiling water.

1)When water is heated to 100 degree C, bubbles can be seen rising through the water. What do these bubbles contain?
(1) Hot water vapour
(2) Hot water droplets
(3) Air dissolved in the water
(4) Only oxygen is released from the hot water


2)When the water boils at 100 degree C, bubbles can be seen. What is inside these bubbles? (1) Air (2) Steam (3) Water (4) Water vapour

Best wishes

tianzhu
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Postby Niedino » Tue May 18, 2010 12:25 pm

Hi Tianzhu,

Using logical thinking (a science process skill) boiled water does not contain oxygen (a common examination question is that why do fish not survive when they are put into cooled boiled water). The bubbles in boiling water can then be attributed to hot water vapour (which is steam, since there is a conversion of liquid to solid state) and some dissolved air in the water (the dissolved air in the water gains heat and hot air rises). So out of the 4 options,

(1) Hot water vapour
(2) Hot water droplets
(3) Air dissolved in the water
(4) Only oxygen is released from the hot water


Option (1) is the best answer and options (2) and (4) are misconceptions.
There may or may not be dissolved air in the water, hence option (2) is not as suitable an answer as option (1).

Just a side note, air is a composite mixture of gases, so this again lends itself to many misunderstandings.

As for question 2, again this is a question that's not set very well, since steam is technically hot water vapour. I would assume that the best answer is steam.

Hope it helps

Niedino
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Re: Pri Science Questions, Concepts and Misconceptions

Postby sunflower » Tue May 18, 2010 12:46 pm

Niedino wrote:Hi all, Thought I'll start a thread on this, as I have come across many common science misconceptions that persist among our children today. As a primary school teacher, I often encounter pupils coming in with misconceptions gained from their incomplete understanding of the scientific phenomena around them. :idea: This would in turn affect their understanding when they go to school.

Hi Niedino, thanks for starting this thread! It's really useful. :D I've got a P6 child and am sometimes confused myself with all those misconceptions.

sunflower
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Postby tianzhu » Tue May 18, 2010 1:03 pm

Hi Niedino

Thank you for your quick response. We would appreciate it if you could help us to interpret this experiment.

Image
Image

Which properties of the brown gas are shown by the above experiment?
A: It can be compressed.
B: It has no definite shape.
C: It has no definite volume.

A.A only
B.A and B only
C.B and C only
D.A, B and C only

Does this experiment show that air can be compressed? How do we interpret the movement of the coloured gas from a smaller container to spread out to two containers?

Best wishes

tianzhu
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Postby Niedino » Tue May 18, 2010 1:22 pm

Hi Tianzhu,

To respond to the earlier question, again, this does not show that air can be "compressed". It shows that air has no definite shape and no definite volume. I would go for option (C). As for the movement of the gas upwards, since air can be compressed (thus resulting in higher pressure), air can also be "stretched" (thus resulting in lower pressure). Opposite of compression is tension.

Another way to look at it is that compression is a "push", while tension (stretching) is a "pull". So the movement of brown air upwards into the round space shows that air can be "stretched" since the air was "pulled" to fill a bigger container, not "pushed" into a smaller container like compression.

This is just my opinion. Some answer keys may justify that since you can show that air can "stretch", you can also infer that air can be "compressed" but I do not subscribe to this logic.

Hope it helps.

Niedino
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Postby tianzhu » Tue May 18, 2010 1:29 pm

Hi

Thanks for starting this thread, it gives me a chance to relieve my bottled up doubts.

Some hot cakes and pies were placed under a transparent plastic hood. After a few minutes, water droplets are observed to be formed on the under surface of the hood. Explain why water droplets are formed on the underside of the plastic food cover.

The quite standard answer is Hot water vapour from the cakes/pies condensed on the cooler surface of the food cover to form water droplets.

If it is a cup of hot Milo, it is easier to comprehend where does the water vapour come from,but in this case I’ve often wondered where does the water vapour come from?

Best wishes
Last edited by tianzhu on Tue May 18, 2010 2:04 pm, edited 1 time in total.

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Postby tianzhu » Tue May 18, 2010 1:33 pm

Niedino wrote:Using logical thinking (a science process skill) boiled water does not contain oxygen (a common examination question is that why do fish not survive when they are put into cooled boiled water). The bubbles in boiling water can then be attributed to hot water vapour (which is steam, since there is a conversion of liquid to solid state) and some dissolved air in the water (the dissolved air in the water gains heat and hot air rises). So out of the 4 options,

(1) Hot water vapour
(2) Hot water droplets
(3) Air dissolved in the water
(4) Only oxygen is released from the hot water


Option (1) is the best answer and options (2) and (4) are misconceptions.
There may or may not be dissolved air in the water, hence option (2) is not as suitable an answer as option (1).

Just a side note, air is a composite mixture of gases, so this again lends itself to many misunderstandings.


Hi
The first question is from MGS Science P5 CA1 2009.

The answer given in the WS is (3).This is a popular question asked in various forums and the answers are usually (1) or (3).

When the water is boiling for some time, the bubbles are made up of steam (water vapour), quite clear cut in this case

When water is heated to 100 degree C, bubbles can be seen rising through the water. What do these bubbles contain?

How do we interpret the underlined phrase? The period when water is heated from room temperature to boiling point? We stop immediately when the moment the thermometer shows 100 degree Celsius? Or we allow the water to boil for some time?

Please share your view.

Best wishes

tianzhu
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Postby Niedino » Tue May 18, 2010 1:50 pm

Hi Tianzhu,

First question, the bun is steamed right? :D so the hot water vapour must be from the bun, since it came from a steamer. More scientifically, the bun has trapped the hot water vapour from the steamer and this then condenses on the cooler surface of the wrap. That's what makes a bun moist. :idea:

Second question, if it is 100 degree Celsius, the bubbles would comprise of entirely or mostly hot water vapour. If I were the setter, the point of me stating that its 100 degree Celsius is to eliminate the answer of dissolved air, as at the point of 100 degree Celsius (boiling point), the conversion of liquid to gas through boiling is the key concept used to answer this question. Regardless of whether you stop boiling at 100 degree Celsius, or continue boiling at 100 degree Celsius, by the time it reaches 100 degree Celsius, it should comprise of mostly hot water vapour (steam).

I am of the opinion that we should teach our kids to interprete the answers to Science questions using concepts they have learnt in school. :D

Niedino
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