Writing a short opinion follows a very simple formula.
The first thing to do is pick a side. No fence sitting is allowed here. State your opinion clearly by restating part of the question and expressing what you think about the idea.
In proving your point, you may quote something you have read, but if there is no reading attached, you may also use evidence from your own experience or from something you have heard from an expert.
eg. Dr Alder, a professor from Applewood University said, "Students are happier when they have less homework."
You would then go on and explain how that quote supports the point you are making.
Always make sure that your evidence and explanation are relevant to the point you are making...
Use the rubric on the right to make sure your writing is clear.