First off, it really depends on your situation. If you are in a well equipped high school, then your bag may be a compartment in your
backpack. I am a resident
stage manager at a college and I still keep everything in my rolling kit with me. I include the following
Pens, Pencils, Eraser, Highlighters (8 colors), post it notes (4 colors), Post it flags (12 colors)(some are off brand), garage sale dots (
cue marking), legal pads (white and yellow), quad ruled pad, looseleaf paper, dividers, copy paper, sharpies (24 colors), scotch tape,
duct tape,
gaff tape,
spike tape (8-10 colors), file folders, clip boards (at least 5), flashlight (two with
gel), paper clips, push pins,
binder clips), hole punch, string, tape measure, scale ruler, first aid kit,
utility knife, sewing kit (5 needles, light thread, dark thread, needle threader, straight pins),
safety pins,
hot glue gun with sticks, stapler (both kind), iPad (longer conversation material), coffee mug...
I am sure I am missing many things but that is off my head. I am a little
OCD and obsessive so some of this may be overkill for you but I find it all and more necessary for me. There are many great articles and several books on this topic.
The best question is "What do I need to get the job done?" It's not a bragging thing to have the biggest kit or anything. Just make you and the actors comfortable. If the actors trust you and your kit then all is good to go.
Someone once compared the
stage manager's kit to a musicians hat. If you can make that
effect of "anything you will ever need" happen for the actors then they are more likely to completely trust you in the show. It is your job to be two steps ahead of everyone else (even the director). Any questions? PM me