I was in your shoes once: a department of one. I went to the shop teacher and asked for his help in building flats. He was happy to help. I showed him what I needed in my old stagecraft textbook.  His class made me the flats I needed in a couple of days. After that his classes made me staircases and doorframes and window flats. It was a great win, win situation. I got the sets I needed, and his class got to build stuff that got used.

I haven't used muslin flats in years. I now make flats out of luan (spelling?). They are just as portable and much sturdier.

Good Luck,

Linda

I agree with the concept of cloth covered flats.  Lighter and safer. 

Look for fabric at upholstery stores....I think it was Gaafa that suggested buying in bulk the fabric used to cover the undersides of sofas and chairs.  It's cheap and wide. I haunt the local thrift stores (mostly for costume pieces) and lucked into about two hundred linen table cloths donated by a catering company....got them all for ten dollars.  Ask the kids to bring sheets from home..everyone has some old ones.  After the fabric is stretched over the frame roll out a coat of good latex primer (nothing too cheap and never oil-based) and then put another cloth over it while still wet and prime that one.....makes a good strong cloth.  If you get tears just put a "band-aid" on it with more strips of cloth and paint.  I squirt a little fabric glue ( available at most fabric stores) onto the wet primer where the fabric will overlap.

I like the idea of having the shop teacher get involved with his class to make the frames but if he can't or won't do it you can make do without frames.  Once the fabric is primed and painted it will be heavier and stiffer and can be stapled to a piece of wood ( like a 2x4) along the top and the bottom and hung from the ceiling (more about that later).  The advantage of this method is that the drops can be rolled and stored.  Make sure that when they are stored they are rolled around a tube (plastic pipe works).  If the drops get folded they will crack.

One of the problems with hanging curtains is that ( particularily in a school) they will have to be certified fireproof.  You might "get away with it" and hang untreated cloth but rules are made for a reason and this is a good one.  Also, to hang properly the curtains must be heavy and you are talking about attaching them to a ceiling....you can't just tack them up.  It will be very difficult for you to devise a way to open and close a curtain so work with plays that don't require elaborate set changes and use brief black-outs to move people on and off the stage.

The simplest way to start would be with one "wall" across the back of the stage area....made of your cloth backdrop hanging about six or eight feet away from the wall.  This gives the students a "backstage".  They can all huddle there (learning to keep quiet) and make their entrances around either end.  To get more elaborate you can hang narrow drops in front of the rear backdrop...four to five feet in front...and make the side drops face the audience.  This gives the actors "wings" that they can enter and exit from and places to stash props.

I have seen some great student sets made with cardboard which - like cloth -  gets stiffer when layered and painted - so tell your students to start collecting big pieces.

If you can afford it and the shop teacher wants to help one of the things that will really help is to elevate your actors...in other words, build them a stage.  Raising them up even 8" - 10" will make a difference.  They will be seen and they will also have the valuable lesson of working within set parameters.  We built a cheap portable stage by getting wooden pallets from the local masonry yard.  Do you know what these are?  - the wooden platforms that hold anything that needs to be picked up by a fork lift.  The local lumber yard might give you some, or a roofing supply company.  Make sure thay are all the same height.  Lay them out in the size you want.  They don't have to be perfectly aligned....there can be some gaps...but they do have to be pretty close together in height.  Then cover them with the cheapest plywood you can get.....we used fiberboard or strand board...you know the kind with the large chunks of wood visible. Screw the plywood down and paint it.  If you get enough pallets you can even make the stage two layers high but make sure the pallets are stable and I wouldn't go any higher than two stacked.

Finally..hanging the drops.  I am still working on alternative methods for this myself but I think it may be best to get the shop teacher or even the maintenance worker at your school to install some permanent attachment points in your ceiling.  You can't  just run a few screws up into the ceiling.  They can bolt some plates directly into the structure of the ceiling and then you can suspend a horizontal rod from wire...kind of like a trapeze.  Then anything you want to hang can be safely suspended from that. Be careful with acoustic tile, suspended ceilings...those metal grids are not meant to hold the weight of a backdrop...

I guess I have blathered on long enough..good luck to you and check in and tell us how you solved your problems....we all have things to learn.