The IB curriculum makes some bold promises. Perhaps the boldest is that it can sum up your mastery of a subject with just one number. Not only that, but this number has the same value no matter the nation or the culture. A 5 in IB Math from a school in New York is the same as one from a school in Jakarta.
How is this done? By applying a curve. This means that students are judged according to other students, not by an objective calculation. The common conception is the Gaussian curve pictured at the top of this post. According to statistics, in a large population traits will be distributed in a certain pattern. In a test setting this means that relatively few students will attain the highest and lowest possible scores, while most of the population will be grouped in a middle range.
As applied in the IB exam, this means that your test results are being compared to every other person on earth who took the test. A huge sample like this gives exam graders lots of data so that they can distribute scores fairly.
Advantages
Here’s how using a curve helps the IB’s assessments:
It encourages competition
Students who know they will be compared to their classmates have a greater incentive to achieve high marks than those who only have to hit a certain percentage of correct answers. This helps prepare them for the real world, when they have to compete for university places or for jobs.
It allows for fairer assessments
Suppose that in this year’s IB Chemistry exam, nobody answers more than 40% of the questions correctly. Does this mean that all of the millions of IB students are woefully unprepared and deserve a failing grade? Probably not. More likely is that the test was much too hard. Using a curve means the IB can know when students deserve a low mark, and when their poor performance might be due to other factors.
Disadvantages
Of course, a system that works for a worldwide assessment like the IB isn’t always suited to a smaller class environment. Here are some arguments against using a curve in schools:
It doesn’t reflect course achievement
Distributing grades according to class position can hide a student’s deficiencies. Theoretically, a student could do quite poorly on a test and still receive a top ranking as long as the others did worse. This is a standard that wouldn’t be applied in the professional world. Suppose you are looking for a contractor to build your house. You wouldn’t hire one whose previous houses have all collapsed three-quarters of the way through construction – even if all the competitors only made it halfway!
It is discouraging to lower-ranked students
Students at the lower end of the curve can be harmed by the system as well. A student who works hard, reviews diligently and answers 90% of the questions correctly can still get a bad grade if his or her classmates managed a higher percentage. In this case, we couldn’t fault our hypothetical student for feeling discouraged. If the best you could do still got you a D, what’s the point in continuing to try?
We can’t deny that the grade curve is a useful tool. But let’s not assume it’s right for all situations too. If you think your class could benefit from a different assessment method, don’t be afraid to speak up!
