assessment must be done carefully and sparingly lest students become so concerned about their achievement (how good they are at doing something — or, worse, how their performance compares to others’) that they’re no longer thinking about the learning itself.
I catch myself worrying more about how I do on exams compared to other students rather than just enjoying learning for the sake of knowledge sometimes. I think it is okay to be tested on your skills and what you have learned, but when students are put into a lower percentile and when scores are posted, it's very intimidating and creates a mentality to try to achieve better than others rather than collaborative learning.