Hi Chuckster
My suggestions to have a proper IP range
a. Create VLANs for every bit i.e Staff, Student (separate it by Grade level, if possible), Guest, Events, IP Phones, Server, Management, CCTV, Access Control. Your printers can be on the same VLAN as the Students computers, staff computers. This would help to create Access Policies for every VLAN i.e Staff at the Primary School with the IP range 10.5.16.x will be able to get facebook access between 10AM-11AM during recess. This won't be the case if a staff in the Senior school is present as ACL (access control lists) is separated.
b. Start with a range that is sustainable with /23 per subnet
c. See how many devices would be connecting at a given time and also try to simulate the number of devices connecting in 5 years time. Always remember students or staff will have a minimum of 2 devices. Multiple that to the staff/student having access
d. Don't go for super scope
e. Don't go for anything below /23, a worst case scenario maximum /22. Anything about this is going to create a massive broadcast storm on the network
f. Don't go with separating IP scopes. Make them under one scope i.e don't put 172.x.x.x with another range of 10.x.x.x. Keep it constant, less headaches
g. When going with /23, first 25 IP should be reserved for various static IP assignments i.e a separate Static IP Printers, Principal etc
h. Make sure and this is the most important, Bonjour addressing if using iPads. Because they don't cross over VLANs/subnets, you need to either put a Bonjour Gateway in between to pass traffic so Students on a particular VLAN can see Airplay devices of Staff on another VLAN.
I. Like another posts says, have 2 DHCP servers and mention them on the Core, Distribution switches, so if 1 DHCP server, other still addresses it.
I hope the above has been useful.
Let me know if you would require detailed info.
Cheers
Joseph