| Index | Arnold | Missouri | National |
| Average Test Scores | 51% | 44% | 48% |
| Student/Teacher ratio | 16:1 | 14:1 | 16:1 |
| Total public schools | 10 | 1,899 | 79,221 |
| Total private schools | 3 | 531 | 24,874 |
| Total post-secondary schools | 2 | 213 | 7,963 |
| Index | Arnold | Missouri | National |
| Completed 8th grade | 83.1% | 86.0% | 84.3% |
| Completed high school | 81.1% | 84.2% | 83.0% |
| Completed some college | 51.0% | 57.7% | 59.4% |
| Completed associate degree | 29.2% | 35.2% | 38.5% |
| Completed bachelors | 19.2% | 27.6% | 30.3% |
| Completed masters | 6.8% | 10.4% | 11.5% |
| Completed professional degree | 1.1% | 2.8% | 3.3% |
| Completed doctorate | 0.5% | 1.2% | 1.3% |
There are a total of 10 public schools, 3 private schools and 2 post-secondary schools in Arnold. Using the proficiency score averages, the average test scores for Arnold, MO schools is 51%. The average student to teacher ratio is 16:1. In Arnold, MO, an average of 83.1% of students have completed 8th grade and an average of 81.1% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Brentwood, MO | 7,986 | 70% | 45.6% |
| Kirkwood, MO | 27,772 | 69% | 43.1% |
| Webster Groves, MO | 22,906 | 64% | 32.8% |
| Ellisville, MO | 9,752 | 62% | 28.1% |
| Ballwin, MO | 30,177 | 61% | 28.0% |
| Arnold, MO | 21,144 | 51% | 5.6% |
| City | Population | Avg. Test Scores | National Avg. |
| Easley, SC | 21,149 | 52% | 7.9% |
| Ashland, OR | 21,138 | 62% | 29.8% |
| Covington, WA | 21,131 | 55% | 13.8% |
| Piqua, OH | 21,159 | 60% | 24.8% |
| Sanford, ME | 21,166 | 43% | 10.2% |
| Arnold, MO | 21,144 | 51% | 5.6% |
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