I think the stethescope thing is a neat idea. You can give a short bandage lesson? Can you get a monitor that makes beeps or lights up? Bring in some scrubs
to "dress up" in? Bring in a pile of thank you cards from people who have appreciated your help? Maybe pictures of different types of nursing jobs (school nurse, ER, operating, doctor office, etc).
If you had some sound bytes of respirations or heart sounds, that would be cool. Let them listen to a normal lung sound, then listen to wheezes, and ask which one sounds normal? Show them where they can locate their pulse? How about a handwashing demonstration with the special lotion that glows in the dark and talk about germs and how you "kill them"? (Which could tie into a lesson on infection, WBC, affectionately called "soldier cells" to help combat infection or spread of disease.) That would be useful information for kids that put their hands in their mouth.
I hope this helped. Maybe even some xrays that they could see in the light would be neat.