| Index | Marietta | Illinois | National |
| Average Test Scores | n/a | 33% | 48% |
| Student/Teacher ratio | n/a | 18:1 | 16:1 |
| Total public schools | n/a | 3,938 | 79,221 |
| Total private schools | n/a | 1,438 | 24,874 |
| Total post-secondary schools | n/a | 306 | 7,963 |
| Index | Marietta | Illinois | National |
| Completed 8th grade | 77.9% | 86.2% | 84.3% |
| Completed high school | 72.1% | 84.7% | 83.0% |
| Completed some college | 30.2% | 61.8% | 59.4% |
| Completed associate degree | 18.6% | 40.7% | 38.5% |
| Completed bachelors | 12.8% | 32.9% | 30.3% |
| Completed masters | 11.6% | 12.7% | 11.5% |
| Completed professional degree | 0.0% | 3.4% | 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 Marietta. Using the proficiency score averages, the average test scores for Marietta, IL schools is n/a. The average student to teacher ratio is n/a. In Marietta, IL, an average of 77.9% of students have completed 8th grade and an average of 72.1% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| London Mills, IL | 326 | 38% | 20.5% |
| Good Hope, IL | 405 | 35% | 27.1% |
| Cuba, IL | 1,066 | 27% | 43.1% |
| Lewistown, IL | 2,021 | 21% | 56.8% |
| Avon, IL | 690 | 18% | 63.5% |
| Marietta, IL | 61 | n/a |
| City | Population | Avg. Test Scores | National Avg. |
| Klukwan, AK | 61 | 50% | 4.2% |
| Yucca, AZ | 61 | 50% | 4.2% |
| Crookston, NE | 61 | 30% | 37.5% |
| St. Charles, VA | 61 | 83% | 71.9% |
| Menoken, ND | 61 | 60% | 25.0% |
| Marietta, IL | 61 | n/a |
Here are the best places to live in Illinois
These are the largest cities in Illinois
Check out the 10 most dangerous cities in Illinois
These are the 10 cheapest cities in Illinois