| Index | Greencastle | Missouri | National |
| Average Test Scores | n/a | 44% | 48% |
| Student/Teacher ratio | n/a | 14:1 | 16:1 |
| Total public schools | n/a | 1,899 | 79,221 |
| Total private schools | n/a | 531 | 24,874 |
| Total post-secondary schools | n/a | 213 | 7,963 |


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| Index | Greencastle | Missouri | National |
| Completed 8th grade | 76.2% | 86.0% | 84.3% |
| Completed high school | 72.0% | 84.2% | 83.0% |
| Completed some college | 29.4% | 57.7% | 59.4% |
| Completed associate degree | 13.1% | 35.2% | 38.5% |
| Completed bachelors | 7.0% | 27.6% | 30.3% |
| Completed masters | 2.8% | 10.4% | 11.5% |
| Completed professional degree | 0.9% | 2.8% | 3.3% |
| Completed doctorate | 0.0% | 1.2% | 1.3% |
There are a total of n/a public schools, n/a private schools and n/a post-secondary schools in Greencastle. Using the proficiency score averages, the average test scores for Greencastle, MO schools is n/a. The average student to teacher ratio is n/a. In Greencastle, MO, an average of 76.2% of students have completed 8th grade and an average of 72.0% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Green City, MO | 520 | 51% | 5.7% |
| Unionville, MO | 1,827 | 50% | 3.5% |
| Novinger, MO | 333 | 40% | 17.2% |
| Milan, MO | 2,429 | 31% | 35.9% |
| Greencastle, MO | 176 | n/a |
| City | Population | Avg. Test Scores | National Avg. |
| Washtucna, WA | 176 | 40% | 16.7% |
| Rockland, ID | 176 | 67% | 39.6% |
| Glacier View, AK | 176 | 50% | 4.2% |
| San Geronimo, CA | 176 | 51% | 6.3% |
| Alpine, AZ | 176 | 65% | 35.4% |
| Greencastle, MO | 176 | n/a |