Oh, neat.
I installed and maintain a 55g in the H.S. I work in.
There are tons of interesting classroom extensions- into water chemistry/toxicology, wave action, circulation, dissolved oxygen, composition of saltwater vs fresh vs brackish, ecological succession, organic waste, temperature and salinity, plant growth etc
Essentially multiple labs and observations to investigate a variety of abiotic factors and their influence on the various organisms in the tank.
I will say that it is easier to stick with a FOWLR for sanity sake.
I started this one as a mixed reef and it was fine for 1 year. Then in the first summer I had issues with custodial crew throwing away my supplies (they thought the bin of rocks 'cooking' was trash....
Or the custodial crew one winter unplugging the lights and pumps over winter holiday and killing the larger fish and all of the coral.
I have never had an issue with the students doing anything bad to the tank.
For the issue of heat...definitely something to consider. In the late spring-summer months I take out the heater.
I also had to do water top off every week because evaporation rate is so high.
For the majority of the life of the tank I used my old T5's.
That burned out this past Sept.
So, I gave them my MH. I wish i had something that provided less heat...because now i have to top off every 1-3 days.
Now...I haven't thought about what I will do when the summer comes. MH plus a sweltering building will not be pretty.
As for taking care of the tank during holidays (winter and summer), I usually have the security guards (they really like helping, but some over feed despite my instructions!) feed daily, and do top offs.
During the summer i try to come in and check on the tank once a week or once every two weeks depending on what I am doing that summer.
That's why I suggest staying with the FOWLR. If it is unlikely that you/someone responsible will come in to check on the tank, do water changes (no one will do that for me), check on equipment AND PUT MONEY INTO THE TANK then the FOWLR is the easiest.
Every year, I put at least $500 into the tank, not counting the equipment I donate from my old set ups i.e. MH, sump, pumps, T5's, etc. I have a very close relationship with Drs foster and smith, and buy from vendors here, and spend a lot of time looking through the FOR FREE posts.
Also, MR and njreefers have been very nice in giving me discounts (vendors) or free/discounted items (members).
Additionally, if you want to add some coral, stick with softies. Some nice zoas, and or GSP or shrooms would look lovely. Also, you can teach about asexual propagation. You can have the students set up frag labs in the classroom.
I also have my students set up phyto culturing stations.
Pm if you have more questions on my experience. I also have an ES HS tank thread somewhere here.