| Orondo School District, WA (District) |
| Orono Public School District, MN (District) |
| Oroville City Elementary, CA (District) |
| Oroville School District, WA (District) |
| Oroville Union High, CA (District) |
| Orrick R-Xi, MO (District) |
| Orrington School Department, ME (District) |
| Orrville City School District, OH (District) |
| Orting School District, WA (District) |
| Ortonville Public Schools, MN (District) |
| Osage, OK (District) |
| Osage City, KS (District) |
| Osage Co. R-I, MO (District) |
| Osage Co. R-Ii, MO (District) |
| Osage Co. R-Iii, MO (District) |
