How should I structure a response? (For example, 'Explain the thought experiment of Mary and the black-and-white room')

The first priority when answering any question, especially in philosophy and exams with limited time, is to look directly at what the question requires you to do, in the case of the example above, explain. Here, however tempting, we should refrain from offering our opinions or rebuttals and limit ourselves to outlining each point in the formulation of the thought experiment, what it means and what it contributes to the argument, finally concluding with the consequence of the experiment and what it aims to show and prove.In early level philosophy, it is particularly useful to structure an argument in terms of premises and conclusions, such as below:P1: Mary knows all physical facts about colour before she leaves her black-and-white room, although she has never seen colourP2: When Mary leaves her black-and-white room she learns what it is like to see colourP3: If Mary learns something, she must learn a factC: There are non-physical factsThis process of structuring will do two things. It will show the examiner you know the content of the argument, and show the examiner you know the logical structure of the argument. Once you have structured the argument like this, the door is open to further explanation -- explaining terms in the premises, for example. However, make sure to not be redundant, markers are on the lookout to dock marks for that.