I actually taught a course based on Educational Research where the students as part of their study to become teachers had to conduct a small scale research project. They always came up with really fascinating ideas. Here are a few:
1) Does listening to music whilst taking tests improve scores?
2) What is the impact of publishing results of work to the entire class? Does it help students to improve?
3) Does the layout of a classroom make teaching more effective?
4) To what extent do students learn better if IT is incorporated into lessons as opposed to traditional teaching?
5) Which teaching approaches appeal more to different learning styles?
6) Does homework actually improve performance?
7) How can feedback on work best improve student performance?
All fascinating topics! Enjoy!