Need help with a child's science question for school

[ExFoedere]

I had an argument with friends regarding my 11yr old niece schoolwork. I want to teach her how to do this correctly.

My understanding is that (2) is correct since the question is trying to get the student to understand that 'reading the thermometer is the way to tell whether is water boiling'.
But some of my friends are trying to argue that (4) is correct too since when water boils, bubbles appear.
What do kiwifarmers think? am I right or do their statement holds water (no pun intended)? and what will be a good way to teach a child to tackle similar questions like these?

I attached the question below, the teacher marked (4) as wrong and (2) as correct.

 

[lolcow yoghurt]

I'd say (2) too. Most liquids remain boiling at the same temperature until they are converted to the gaseous state, then the temperature of the gas can rise.

 

[Tanuki Mixed Nuts]

Its not a particularly well written question, as technically you could use multiple ways to confirm that the water is boiling.

I assume it's looking for 2 because it is the most consistent answer for the setup provided. Bubbles can form before the entire beaker/water is at the suggested temp/boiling point, a flame being on does not confirm a boil is going on, and the volume of water decreasing is not explicitly evidence of a boil.

The question seeeeeeeems to be suggesting that the tools in the experiment are the most useful and consistent method of telling when the boil is happening, and I can only guess that there are similar questions on whether such tools would be more effective than other methods (likely focusing on the tools usually being the best option)

 

[Dieter Hell]

This is a test for children, find something better to argue about.

 

[DJ Grelle]

It can be considered 2 since there are other ways to have water bubble.
However, a thermometer reading 100 C does not always mean that it boils either; water under pressure takes a higher temp and nearing vacuum it takes a lower temp.
Although, when not defined you should generally assume that the environment is 1 atm. 20 C.


Please consult this handy diagram:


edit: coming back to it, the question is simply very ill defined. You can make an argument for 2, 3 and 4 to be correct answers.

 

[Fishcat]

It's an awkward question but my take on it is that it's trying to teach that in the context of a scientific experiment, you need to rely on empirical measurements (2) rather than the casual observations (1, 3, 4) that you might be used to looking at in everyday life. When I was doing lab experiments in school they really drilled in the point that you should not just assume or guess stuff while in the lab, so for instance you should remember that hot glassware just looks like normal glassware, unsafe chemicals can look like water, and eyeballing quantities is not a good idea. The point of the question is probably to teach that "well, it kinda looks like x is happening" is not real evidence that x is happening and that you need to actually check with a relevant tool.

Imo the relevant takeaway for a child student is that when scientists do experiments, they have to be very precise and double check all their observations in order to make sure their data is good and useful, even if it looks obvious. Encourage her to think about some misleading reasons that can make it look like water is boiling when it's actually not (e.g., chemical reaction with another substance can cause bubbles). It's less a question about the physical process of boiling water than about general diligence and methodology in the scientific inquiry process.

 

[DefinitelyNotMe]

Its a children question and that means the termomiter was drawn for a reason and especially that its specificaly tells you the temperature. So the correct answer is supposed to be 2.
But if we are gouning autistic and by the way this question is phrased i would say 4. Water boiling temperature isnt always 100 degrees due to all the shit that can be mixxed with it. So if you want a confirmation on when water starts to boil you have to look at the bubbels.
Its theory vs practice thing.

 

[0 0]

1) Does not mean it is boiling. A water can be above a flame and not boil, or boil without a flame.
2) Is empirical evidence confirming the water is boiling. It cannot not boil while the thermometer reads a consistent 100 degrees in normal conditions.
3) Irrelevant, water can evaporate without boiling.
4) Is qualitative and subjective.

The exceptions for 4 are not reasonable to assume. Corrine is not in outer space or on a nuclear submarine.

 

[Your Starter for 10]

If it's public school just have her write in "When the water identifies as boiling, it is boiling."

 

[GeorgeWashingtoff]

2, 3 and 4 could be technically valid.

I used to hate badly written ambiguous questions at school.

 

[BScCollateral]

"Remains at a stable temperature over time while heat is being added" is correct. 100 C requires pure water and standard pressure. #2 is incorrect if the school is in Denver.

 

[W'rkncacnter]

Very unfortunate name, Corrine.

I'd say it's 2 as it's a science question and they want the science-y answer. Also, you can have bubbles form without the water being 100 degrees you'll notice it if you're boiling water for pasta or whatever. You get small bubbles on the sides or the bottom of your pot before it reaches 100c. So therefore bubbles forming =/= boiling. You right, friends wrong.

 

[Sparkletor 2.0]

Can't water be superheated to over 100°C and not be boiling? Like if you put it in the microwave for a long time, it will be over the boiling point and any disturbance will cause it to instantly boil and explode. Same thing with super cooling where water can be below zero and still be liquid until disturbed. So I think water can be 100° and not be boiling.

I could be wrong but I think that boiling technically refers to a liquid changing into a gas. So I would say the appearance of bubbles means that boiling is taking place.

 

[BScCollateral]

Can't water be superheated to over 100°C and not be boiling?

Yes. In order to boil, water needs nucleation points. In a chemistry lab this is done by adding boiling chips (broken ceramic).

 

[Sangue e terra]

• Not 4: Since you can have stuff that evaporates at lower temperatures in this liquid (water containing other stuff) or even have a reaction to the container that creates bubbles. Some prick smeared some magnesium powder onto the surface of the container to trick you.
• Not 1: Since the heat source doesn't matter. It could be boiling due to the room was 100 degrees or the container was already hot. If you turn off the heater, it could still be boiling (for a short amount of time).
• Probably 2: Since you can not "add" extra thermal energy to the liquid (assuming constant atmosphere pressure). "Temperature = kinetic energy", too much the particles will start to overcome the Van der Waals and "become" gas. Use thermal phase diagrams.
• 3 is a little vague (depends on the time span the experiment takes place it): Since with time, evaporation can happen below the boiling point, but when boiling, you are "accelerating" this. You can use this fact to confirm that it's not number 4 at least.

So, I would say number 2 is the "correct one" (or what the teachers are looking for). But again, kids questions... vague and a little dumb since the answers are entangled. If you want to be really heckn soyence™, how do you know that the thermostat is even showing correct? You can make a confident judgement with point 1,2, 3 and 4 together, not just one of the points.

 

[Sparkletor 2.0]

Yes. In order to boil, water needs nucleation points. In a chemistry lab this is done by adding boiling chips (broken ceramic).

So if I am understanding, water can boil at 100° but won't necessarily boil unless there is a nucleation point to trigger the physical reaction. Therefore until the liquid actually undergoes a physical change into gas it is not boiling.

 

[David Brown]

The thread title would make an honorable mention for random.txt in my opinion

 

[Nicholas Gur]

Clearly more conditioning to punish children for intuitive reasoning over the scientific consensus. I refuse to surrender this under the guise of ignorance either, The material is not being manufactured in house by the teachers.

 

[Gobermental Supervisor]

First, the question is moronic, because a liquid can boil without any visual indicators.
"Boiling" is defined as a "exceeding its boiling point".

The question does not define if the water is typical table water or demineralized water, which is often used science class. Demineralized water, depending on purity, can boil without showing the typical "rolling boil" bubbles, these are only always present in normal water with the normal mineral impurities.

A perfectly still body of demineralized water can exceed the boiling point of 100°C and introducing an impurity can cause a spontaneous "explosion" due to instant formation of gas bubbles. The process is called "Siedeverzug" in German.

If the goal of these tests is to teach children how to safely handle potentially dangerous chemicals, by teaching ground rules, then ONLY the Thermometer answer is correct. A rolling boil is NOT always present, and teaching children to look for that in the context of a science class would be stupid.

Here is a tame example of the phenomenon:

Loading…

www.youtube.com

 

[The Skeksis Emperor]

It's an awkward question but my take on it is that it's trying to teach that in the context of a scientific experiment, you need to rely on empirical measurements (2) rather than the casual observations (1, 3, 4) that you might be used to looking at in everyday life.

Agreed, the key word here is 'confirm'. If the water bubbles, you can assume fairly that the water is boiling; however, in the context of a scientific experiment, you can only confirm this if you measure. So 2 is correct.

The problem with some of these questions in math and science is that they are sometimes less about math and science and more about understanding the question and the words used. I've seen students who are good at math fail hard with very descriptive questions, because they're not so good at interpreting the question exactly right. For myself as a kid it was always the opposite, since I was good at language comprehension but not at hard math.