Answer:
Acting with derision, on the part of a student, means that that person believes him/herself as superior to others, or is intolerant of the differences of others, or simply thinks that life is to be lived by laughing at the expense of another´s mistake. Pride, can also be a causant for this, or, in some cases, also a defensive mechanism of someone who is deeply insecure himself, but tries to cover it through derision.
In any of these possible scenarios, however, it is important for a teacher to have techniques ready to dissuade the situation, prevent the damages to the one suffering the derision, and correct the one doing the action, while at the same time teaching the other students how to manage such a situation.
As such, there are some things a teacher might do:
1. Make emphasis on the fact that there is no reason to laugh, as everyone makes mistakes, including the teacher himself. And everyone has the right to make them, without being laughed at.
2. Engage the students at the group to share the silliest mistakes they too have made, and include the teacher himself, so that there is an understanding that mistakes are not a bad thing.
3. Finally, you can literally ask the group to stop laughing.