How many concurrent devices can run on Bluetooth at the same time?

Hi there, I am in need of some help on figuring this problem out. So there has been a lot of debate and mixed information all over online about Bluetooth connectivity. Many sites are confusing "pairing" with "connected" so the answers have been pretty vague. In my current situation I am trying to find out if I can connect 12 keyboards to a single Bluetooth at the same time with all 12 simultaneously being used for a classroom program with students. Is this possible?

Currently the program we run works by using wireless USB dongles, but it's a mess to keep inventory with considering I am going to have to order and manage over an additional 150 keyboards, USB multitaps, and batteries for the school. Trying to simplify it by using rechargeable Bluetooth keyboards but am afraid to put down all that money for it not to work out in the end. Thank you for the help.