| Index | Diagonal | Iowa | National |
| Average Test Scores | 78% | 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 | Diagonal | Iowa | National |
| Completed 8th grade | 85.4% | 89.2% | 84.3% |
| Completed high school | 81.7% | 87.7% | 83.0% |
| Completed some college | 46.3% | 59.8% | 59.4% |
| Completed associate degree | 28.8% | 38.4% | 38.5% |
| Completed bachelors | 12.5% | 27.2% | 30.3% |
| Completed masters | 2.9% | 8.7% | 11.5% |
| Completed professional degree | 0.0% | 2.7% | 3.3% |
| Completed doctorate | 0.0% | 1.1% | 1.3% |
There are a total of n/a public schools, n/a private schools and n/a post-secondary schools in Diagonal. Using the proficiency score averages, the average test scores for Diagonal, IA schools is 78%. The average student to teacher ratio is n/a. In Diagonal, IA, an average of 85.4% of students have completed 8th grade and an average of 81.7% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Mount Ayr, IA | 1,988 | 83% | 73.4% |
| Lenox, IA | 1,446 | 73% | 52.6% |
| Afton, IA | 901 | 71% | 47.4% |
| Diagonal, IA | 475 | 78% | 61.5% |
| City | Population | Avg. Test Scores | National Avg. |
| Garden Valley, ID | 475 | 60% | 24.0% |
| Kinde, MI | 475 | 35% | 28.1% |
| Bonanza, OR | 475 | 41% | 15.1% |
| Glasco, KS | 474 | 38% | 21.9% |
| Melrose, WI | 474 | 42% | 13.5% |
| Diagonal, IA | 475 | 78% | 61.5% |
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