Hi hager,
still the description is not clear. You need to explain what is your study design, which are your predictors, what is your outcome.... Is it qualitative or quantitative?
I would suggest to read "Discovering statistics with SPSS" from Andy Field. It helped me loads to get started with statistics. Also, since you have students in classrooms, your observations are not independent, so you will probably have to use multilevel modelling.
If you give more details, I might be able to be more specific.