| Index | Castalia | Iowa | National |
| Average Test Scores | n/a | 69% | 48% |
| Student/Teacher ratio | n/a | 13:1 | 16:1 |
| Total public schools | n/a | 1,101 | 79,221 |
| Total private schools | n/a | 208 | 24,874 |
| Total post-secondary schools | n/a | 96 | 7,963 |
| Index | Castalia | Iowa | National |
| Completed 8th grade | 85.4% | 89.2% | 84.3% |
| Completed high school | 82.1% | 87.7% | 83.0% |
| Completed some college | 39.1% | 59.8% | 59.4% |
| Completed associate degree | 23.8% | 38.4% | 38.5% |
| Completed bachelors | 16.6% | 27.2% | 30.3% |
| Completed masters | 3.3% | 8.7% | 11.5% |
| Completed professional degree | 1.3% | 2.7% | 3.3% |
| Completed doctorate | 1.3% | 1.1% | 1.3% |
There are a total of n/a public schools, n/a private schools and n/a post-secondary schools in Castalia. Using the proficiency score averages, the average test scores for Castalia, IA schools is n/a. The average student to teacher ratio is n/a. In Castalia, IA, an average of 85.4% of students have completed 8th grade and an average of 82.1% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Decorah, IA | 7,615 | 81% | 68.5% |
| Calmar, IA | 989 | 80% | 66.7% |
| Elgin, IA | 638 | 78% | 62.0% |
| Waukon, IA | 3,663 | 76% | 58.0% |
| Ossian, IA | 798 | 75% | 55.2% |
| Castalia, IA | 169 | n/a |
| City | Population | Avg. Test Scores | National Avg. |
| Troutdale, VA | 169 | 87% | 81.3% |
| Westphalia, KS | 169 | 40% | 16.7% |
| Binford, ND | 169 | 20% | 58.3% |
| Vernon, AZ | 169 | 40% | 17.7% |
| Farmington, CA | 169 | 35% | 27.1% |
| Castalia, IA | 169 | n/a |
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