I think the individual schools could use either VHF or UHF simplex on campus. My high school in Jeffco used 154.600 and 154.57 when I was there (over 10 years ago). They actually had a license, believe it or not! Any of the VHF/UHF itenerant frequencies like these or 464.500, 464.550, or 151.625 would be good to try.
I know some schools in Jeffco have their own UHF simplex frequency licensed to them. Arvada HS has been licensed on 466.6875 for years. I haven't verified that they use it, though.
The old Jeffco Schools security repeater (before they went DTRS) on 461.925 with a 131.8 tone had a little bit of maintenance activity on it, last I checked. I have heard several schools using 461.925 simplex with different PL's, so this would be a good one to try, as well.