Was this Teacher Too Harsh?

We look at a decimal rounding test where a student was penalized heavily for not including trailing zeroes when rounding. Was this fair? Why did he lose points? We'll look at the problems from r/askmath and the solutions in this video. #maths #mathematics

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0:00 Intro
1:47 Student Thought
2:37 Measurement
5:20 Rounding
9:44 Discussion
13:19 Conclusion

[WrathofMath]

have not thought about reality in a long time!

[Aweman]

The teacher tried to give half marks but they got rounded down.

[georgecataloni]

The context isn't missing. It's 5th grade. Of course they weren't taught the importance of measuring precisely. They're just learning how to round.

[sandekv]

This is why people hate math. In my opinion, the kid got 1 answer wrong. This is math, not physics or chemistry or anything. Significant figures don't exist in pure math, math is perfect and theoretical.

I would have at least given half marks for everything except the one the kid actually got wrong. They clearly know how to round, their issue is removing significant figures if they are trailing 0s.

[willemm]

Given that there are six questions on the test where you have to put ending zeroes, one could argue that the test setters rated "not knowing you're supposed to keep the trailing zeroes" as about six times as bad as "making a calculation error" by specifically adding six cases where this would trip a student up.

[klieu]

If significant figures aren't specified beforehand, you can't reasonably mark those incorrect.

[penguincraft]

Damn a grade 5 maths test just started a whole ethical debate

[davepost]

In either case, the teacher doesn't understand rounding. 25/32 = 78.125% and that does not round to 79%. So unless the teacher taught the students the ceiling function, then I would lean towards the teacher not intending to teach the value of significant digits.

[kevinchan]

There is no rule in math that you need to communicate the precision to which a number was rounded. The question did not ask for significant figures. It asked for rounding, which is NOT the same thing.

Sure, if you have a measurement that needs to be rounded, then you do include trailing zeros. However, this test involved rounding pure numbers, not measurements. In addition, significant figures are rounded to a specified number of digits, NOT to a specific decimal place.

If the teacher wants to teach a skill that's used in practical applications, it should be presented in the proper context. Treating it as a general rule for mathematics is wrong.

[Timorr]

3:37 I am NOT falling for that rage bait

[lily_littleangel]

3:25 "those are the smallest markings"
The humble millimeter:

[janzwendelaar]

I would think that mathematically, the student's answers are correct.

As an engineer, sure. 35 means something different than 35.0, but that's got to do with error margins, not with mathematics. This is a maths test, not a science test. There 35==35.0==35.00

[random.studios]

Me to the cashier: Here's 10 dollars
Teacher to the casher: "10 dollars and *zero cents* " 💀

[DugdoesDigging]

if this is a science class: sure
If this is a math class: after the first incorrect point, don't take any more

[FScott-mn]

Demanding a .0 sounds like a sig fig requirement, not an necessary expression of tenths... but then again it's been a few decades since I had middle school math.

[chrism.]

At no point in my school years was I penalized for something as petty and inconsequential as that, or I would vividly remember losing my marbles.

[kupa]

I agree more with the student. Imo the question isn't worded clearly enough, in Poland we never did it this way, so I would have made the same mistake. Unless the teacher explained in his previous lessons that this wording of the question means they *must* do it this way the teacher is very much in the wrong.

[veedrac]

It's honestly so silly that this even has a ‘grade’. The only coherent use of a test like this is to create shared knowledge between the student and teacher over which parts of the syllabus were understood. Going along and counting which fraction of the test questions rounded to a higher power of 10 is completely irrelevant to anyone's actual educational achievement, and serves only to distract from the point of it all.

[ImaginaryMdA]

What I think is a shame, is that the student really only misunderstood 1 concept, but was marked down over and over for this same mistake.

[TheInevitableHulk]

For a 5th grade math test, it seems like the teacher is testing for these two different concepts but worded the test in terms of only rounding.