Marked unfairly? (1 Viewer)

[Scodger3]

In our last chemistry exam we got marked down for not rounding off to at least 3 decimal places even though they did not specify what accuracy was required for our results. They are taking marks off us for not rounding off even though it was not stated that we needed to! Is this allowed? Or is their a board of studies rule that prevents them from this? Thanks.

 

[strawberrye]

lol, I don't think the board of studies have a specific rule that prevents teachers from doing this, they would be unable to predict every possible situation, like all laws-constructed by humans, inevitable that there will be some flaws, so I don't think you can report this to board of studies and be successful...

When you say you got marked down for not rounding off to at least 3 decimal places, do you mean a lot of people just write more than 3 decimal places? or did they just round down to 2? It also depends on the question and the data within the question, it is not an explicit rule, but it is generally a fact that if the question has data to 3dp, this includes 0, i.e. 3.100, your answer should only be three decimal place max, because if you have more than 3 decimal places, it is impossible to get a value to an even greater accuracy/precision than the original measurements(data from the question)that it was extracted/analysed from. So although it may not be in the question of how many decimal places you have to round off, but your teacher may have told you in the past or assumed you know certain rules relating to rounding off-do you by any chance remember they telling you that?

As long as if the teacher had marked consistently-i.e. they marked down all the people who didn't round off-I think it is hard to report this to the head teacher or say they are not allowed. Although in hindsight you may feel it is vastly unfair, but what you can take from this is to take the responsibility to ask teachers about their requirements, i.e. answering questions rounding off before future assessment, and perhaps ask them to explain to you why you got marked down for not rounding off-i.e. will there be an implication for later errors or harder to draw a graph accurately if not rounded off if a graph was required...

Ask your teacher for a reason and learn a lesson from this-life can never be absolutely fair you just have to make the best of everything and hope next time, this doesn't happen again hope this helped

 

[obliviousninja]

In our last chemistry exam we got marked down for not rounding off to at least 3 decimal places even though they did not specify what accuracy was required for our results. They are taking marks off us for not rounding off even though it was not stated that we needed to! Is this allowed? Or is their a board of studies rule that prevents them from this? Thanks.

Its all relative though isn't it? ie, everyone lost marks. If not, go to your head of science teacher.

 

[madharris]

Your teachers have a marking criteria that they create and follow while marking
If you don't meet this criteria then you will lose a mark
It's good practice to instinctively think to always round off to the appropriate number of significant figures

 

[RealiseNothing]

In our last chemistry exam we got marked down for not rounding off to at least 3 decimal places even though they did not specify what accuracy was required for our results. They are taking marks off us for not rounding off even though it was not stated that we needed to! Is this allowed? Or is their a board of studies rule that prevents them from this? Thanks.

You HAVE TO round off to a certain amount of significant figures, it's actually a rule in science.

 

[anomalousdecay]

You HAVE TO round off to a certain amount of significant figures, it's actually a rule in science.

Yeah this. You round off to the significant figures given in the question. If the value given is 3 significant figures, your answer should be in the same form.

 

[obliviousninja]

Yeah this. You round off to the significant figures given in the question. If the value given is 3 significant figures, your answer should be in the same form.

OP specified, nothing given. I have no idea about chem/phys if its standard protocol for 3, for accuracy measures.

 

[RealiseNothing]

OP specified, nothing given. I have no idea about chem/phys if its standard protocol for 3, for accuracy measures.

It doesn't have to be given. Suppose you had 0.5M of a substance in 0.5L of whatever and you wanted to find the moles. Using n=CV you get 0.25moles, however the question only uses values to 1 sig fig, so your answer has to be 0.3 moles.

 

[panda15]

It doesn't have to be given. Suppose you had 0.5M of a substance in 0.5L of whatever and you wanted to find the moles. Using n=CV you get 0.25moles, however the question only uses values to 1 sig fig, so your answer has to be 0.3 moles.

This. You round to the least accurate measurement given. Say that you are given two values 1.0 and 3.500, and you need to find the average. Although the answer is 2.25, the least accurate measurement is 1 sig. fig, so the average is rounded up to 2.3.

 

[RealiseNothing]

This. You round to the least accurate measurement given. Say that you are given two values 1.0 and 3.500, and you need to find the average. Although the answer is 2.25, the least accurate measurement is 1 sig. fig, so the average is rounded up to 2.3.

2 sig figs*

 

[panda15]

2 sig figs*

Sig figs always fucked me over haha

 

[anomalousdecay]

It doesn't have to be given. Suppose you had 0.5M of a substance in 0.5L of whatever and you wanted to find the moles. Using n=CV you get 0.25moles, however the question only uses values to 1 sig fig, so your answer has to be 0.3 moles.

Yeah this.

 

[someth1ng]

It's too vague to give a decent answer - it's NEVER "at least" X decimal places or X significant figures - it's always X significant figures, no more - no less.

You can lose marks for not being the correct significant figures.