| Cassia County, ID (ISD) |
| Cassia County Joint District, ID (District) |
| Cassopolis Public Schools, MI (District) |
| Cassville R-Iv, MO (District) |
| Cassville School District, WI (District) |
| Castaic Union, CA (District) |
| Castine School Department, ME (District) |
| Castle Rock School District, WA (District) |
| Castle Rock Union Elementary, CA (District) |
| Castleberry ISD, TX (District) |
| Castleford District, ID (District) |
| Castlewood School District, SD (District) |
| Caston School Corporation, IN (District) |
| Castro County, TX (ISD) |
| Castro Valley Unified, CA (District) |
