Tutor Niedino: Pri Science Questions and Concepts

[tianzhu]

Niedino:

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

[Niedino]

Hi Tianzhu,


First question, the bun is steamed right? 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.

[Niedino]

Just a side note, since the answer from the WS is 3, it reminds me to warn everyone that when you purchase exam papers from shops etc …, the answer key given is not standardised. I often find mistakes in the answer key.


Teachers have to standardise their marking and allocation of marks so our answer keys are much more detailed and elaborate then the ones found in shops.

Science marking looks at the identification of key concepts by the students. Perhaps if I have some time in the future, I can shed some light on how you can help your child write better Science answers.

[tianzhu]

Hi moderator.


Please delete.

Thanks

[tianzhu]

Niedino:

Perhaps if I have some time in the future, I can shed some light on how you can help your child write better Science answers.

Hi

That’s would be great. We don’t usually have a science teacher in KSP who is as actively involved as you are today. Your presence is as rare as Manchester United playing in our National Stadium.

Best wishes

[I_belive]

tianzhu:

Niedino:

Perhaps if I have some time in the future, I can shed some light on how you can help your child write better Science answers.

Hi

That’s would be great. We don’t usually have a science teacher in KSP who is as actively involved as you are today. Your presence is as rare as Manchester United playing in our National Stadium.

Best wishes

Yeah, Agree with you!

[Niedino]

Hi,


I noticed that my topic has been moved up to the stickies. Can I request to remove the word "Teacher" from the title. Just niedino would do, as I’m posting in my unofficial capacity.

Thanks

[tianzhu]

Hi moderator


I think the key word Misconceptions is missing from the header.
As the TS started this thread to help clear up misconceptions for primary science, it may be more appropriate to add Misconceptions to the thread’s title.

Please consider changing the header to

Niedino: Primary Science Questions, Concepts and Misconceptions

It reflects better the intention of TS.

Best wishes

[Niedino]

I thought of starting with a powerful Science Misconception.

Here's a misconception of the week for all.

Is a seed a living thing?

Lets' hear some responses before I post ok? (Professional Sickness) :lol:

[atutor2001]

Niedino:

Hi Tianzhu,


.....

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. ....

At last we have a real expert in primary science concept. Thank you. All parents don't miss this thread.