Are you talking about the teaching of the "nurse theorists" such as Watson, Orem, Roy, etc.? .... Or are you using the term "theory" to apply to the any didactic lecture material. (Some schools call all their didactic content "theory.")
I teach the actual nursing theories (Roy, Rogers, etc.) in an RN-BSN program. My class is evaluated positively with most students saying things like, "I was really dreading this class, but it was much more interesting than I thought it would be."
I approach the topic from a historical perspective, covering the major theorists chronilogically, starting with Nightingale. We talk a little about the context of each theorist's time, the needs of nursing at that time, and what important conepts or ideas that theorist added to the conversation about nursing.
I raise questions such as "Which ideas are still relevant today?" "Can we see how this particular theorist's work builds on the work of the theorists who came before her?" "How could someone use this theory to plan their patient care?" "How might someone use this theory to conduct a research project to learn more about this topic?" etc. Examples from the literature are used as examples.
One homework assignment I particularly like is this: I have a paragraph case scenario. The class is divided into 3 groups. Each group uses a different theorist's work to organize their care. They discuss how to apply that theory to this scenario -- then share their conclusions with the class. During class we discuss how each group approached the patient a little differently because they were using a different theory. We do this assignment early in the semester. Then we have it to use for the rest of the semester as we explore additional theories.
Perhaps most important, I don't treat the theories as "sacred cows." They are simply frameworks that different people have come up with to help organize their thoughts. We "play" with them in the class -- explore them, appreciate their good points, and feel free to criticize their weaker points. By the time we get to the end of the semester, we have covered a lot of historical territory and are ready to talk about the current state of nursing theory development and use in the last class. (e.g. the Magnet Recognition Program's requirement for a "Professional Practice Model")
Their final paper for the semester requires them to pick any theory studied in class, review an example of its use in 1 article they find in the literature, and discuss 1 example of how they could use that theory in practice. They also need to briefly summarize the theory and say how it relates to their philosphy of nursing as part of the paper.
It may not be the best theory class ever taught (and I didn't design it originally. I have just tweaked it a bit since I took over that job). -- but it is successful and fairly well-lliked by the students. My biggest problem is that I have yet to find a textbook I like for the undergraduate level students.