how to set noproxy and proxyblock per client ip

hello and thanks for reading this.
i am helping a school with a lan connection.
the school has some very young children that need to have their internet
access limited yet the administration need to be handled differently.

i am a windows guy and i have been using microsoft proxy server.
i have been writing and isapi in visual c++ but it is a nightmare to debug.

so i am trying apache as a forward proxy server and i am loving it.
i know that i can use the noproxy and proxyblock directives.

my problem is that i want to set noproxy and proxyblock based on the client
who is trying to access the page.

for example,
in the student lab, these machines, each having a unique ip address, should
have all sites block except those on a white list.
but for administrators, they need almost unstricted access. maybe blocking a
just few sites.

i cannot seem to create this functionality using the apache.
i have spent a few days thinking about this and i cannot figure it out.

thanks,
dave