Networking at school. How to be?

Question

Computer networks

The task is next.
There is a school in the suburbs. The network equipment is extremely bad and old (even hubs seem to be used for switching). Now the question has arisen of the need to raise a normal nimble network, since exams must be held and in general, the 21st century is in the yard. The admin is wooden so much that he can hardly even cope with the installation of Windows. I just lead a programming circle there 2 times a week and as such I am not a system administrator, and if I am, then only occasionally, because sometimes I have to perform these functions at work. But I'm the one to use the net, so I offered my help. And the first question arose with the purchase of new equipment, because what we have now works very poorly, and in general, no one knows how it works. Which of the given we have:
The optics goes directly to the school, where, through simple transformations, it goes into a twisted pair, which we have on the router installed by the company that provides the Internet. The router there is D-Link DIR 300. There are also 3 computer classes with up to 16 computers each, and all 3 classes are located as far as possible from each other. All of them are interconnected by the very hubs that I indicated above. + to all this, in elementary school, you need to make Wi-Fi (4 rooms per floor, 2 floors). The elementary school is in the same building as the computer labs. Wi-Fi is also needed in the center of the school itself. + one of the routers needs a DHCP server. Actually, the question is what equipment is best to look at from a price / quality point of view? As you understand, it will be necessary to replace these 3 hubs, Yes, buy normal Wi-Fi routers (you need a separate network to have Internet access, but there would be no access to the main network), which would well break through about 4 reinforced concrete walls about 40 cm wide (so that everyone would have enough in elementary school). I really appreciate your advice and help. And what to do with this D-Link's router, through which the entire Internet now goes? You can replace it, but what to put in its place?

Answer 1

1. You decide, either you have everything reduced to one point "server room", or you have several intermediate switches / switches
   also don't forget that
   Sorry for the mistakes, but somehow it looks like this at school, if without TK / tenders and not "adult"