I spent one summer working in a research lab during my undergraduate degree. Now that I am in 4th-year and applying to graduate schools, my former supervisor has asked if I would like to join his group.
I had an enjoyable experience in his group, but I think my talents lie towards the theoretical side of my field (physics). To be perfectly honest, I think that it is more likely I will choose something other than his group. At the same time, I don't want to "rule out" the possibility of working with him just yet because I can see myself being happy with either scenario (his group or somewhere else).
So my questions are:
How do I politely tell him that I am interested, but I want to consider other options too? How transparent should I be with my interest in theoretical research over experiment? Would it be best if he knew that his group would probably not be my first choice?