If you have chosen a specific concentration to pursue in your education program, it will be beneficial to choose a topic for your thesis within that field. For example, if your degree will be in special education, choosing a thesis that deals with autism, dyslexia, speech impediments and other learning disabilities is a good approach. If you want to teach children's literature, you could discuss the benefits of story hours and parental involvement in a child's reading.
Writing about a topic that is of personal interest to you will help the writing process and make it easier for you to talk about the topic when it comes time to give your presentation. For example, if you were home-schooled as a child you could research home-schooling techniques and benefits. Perhaps you have a special interest in children's literacy rates; your thesis could focus on this topic.
If you know what area or age level you want to teach in, focus your thesis on a related topic. For example, if your degree will be in early childhood education, your thesis might by about the development of motor skills in the classroom or about teaching writing and reading techniques. If you want to teach in a secondary school, your thesis could be about motivating students in the classroom or peer-editing techniques.
Your professors and the committee to whom you will present your thesis will be looking for originality in your topic and research. When going about deciding on a topic for the thesis, see how many other theses exist that relate to the topic. If there are too many similar theses, think about a distinctive way to conduct the research or present the information. For example, there will be many papers written about the benefits of having recess in elementary schools, but you can conduct research like interviewing students and parents to get different perspectives.