Thanks for reaching out. I can personally assure you that 3D printing, while an incredibly powerful tool, is nowhere near as daunting as it seems! With a little information, we can definitely get you folks going.
First of all, do you have some ideas of what you would like the students to create? Or, at least, your learning objectives for the printing experience? What you want the students to print will determine which printer capacity we'll send over to you, which will, in turn, determine which filament and software you will use.
Makerbot and Afinia printers each have their own filaments. We'll provide you with some to get started, and you may need to purchase more, depending on the volume of the pieces that are being printed. But don't worry! We'll send you a link to the exact type of filament to buy.
Both Makerbot and Afinia printers also have their own freely downloadable operating software, which essentially acts as the interface between your design and the printer hardware. You can have the students create and export their designs on any 3D modeling software, and simply import the STL file to the printer's respective operating software for printing. Think of downloading your digital photos and getting them printed.
I'll follow up more with you offline, but here's a link to get you started: https://stempreacademy.hawaii.edu/subject/3d-printing