If anyone's struggling to answer the research method question its actually quite simple and iv'e (my teacher lol has) broken it down into two steps:
Step 1: Forget about the method you have chosen completely, for now. Come up with general issues regarding the context (these issues are usually practical ethical theoretical ones) The context is usually what the researcher is studying ie setting and streaming, but remember forget about how they are doing it!
Step 2: Does the method chosen improve the issues or does it make it worse
ie: one of the issues that arise with investigating setting and streaming is that access to the school may be difficult as consent is needed. However questionnaires help solve the problem of gaining access to the school because they can be just sent via post to the school.
Just repeat this through the essay also if the method makes the issue worse suggest other methods that may be better but dont write too much on it because the question is asking specifically to asses the use of your chosen method!