I have been working with Professor 1 for a semester. He has been very helpful and we have spent some time together this semester discussing problems. I enjoyed working with him and also find his research interesting.
However, there is also this other Professor 2, whose work I find interesting and he works in related areas. So, I want to work with Professor 2 for a semester before deciding whom to stick with.
Meanwhile, I want to continue the work that I have initiated with Professor 1. I want to convey this message to Professor 1 in a manner that will leave the possibility of working with him after next semester open. So, how should I tell Professor 1 that I want to do a small project with Professor 2 to try out things, without sounding rude?