A "smart" board is just a touch sensitive surface that is recognized by the computer as pretty much a standard mouse. It plugs in through USB. The only thing "smart" about it is that there are a few extra sensors on the board that identify which color "marker" you're using (simple IR sensors in the holders) and a calibration button.
It's no smarter than the touch surface on your tablet or phone.
It's pretty much the worst investment a school can make, but the alternatives somewhat require a resident nerd willing to put in the effort to assembly them. I'm checking the price on Alibaba for a 48" x 96" infrared overlay. If I can get it for $300 a less I'll buy it and see how it goes with my own set up at my house.
Frankly, a $100 document camera and a simple whiteboard are perfectly sufficient for 90% of what a "smart"board is used for.