Summary:
Sullivan has one high school, Sullivan High School, serving grades 9–12 and enrolling 317 students. The available results show a sharp divide by grade: grade 10 PreACT scores are above Illinois rates, while all three grade 11 ACT results are below them. The most important takeaway is that the school’s overall results hide very different outcomes across grades.
As the only high school in the area, Sullivan has no local school peers to rank against; its strongest latest results are in grade 10 ELA and science, while its weakest are in grade 11 science, ELA, and math. In grade 10, proficiency was 69% in ELA, 43% in math, and 64% in science—15, 7, and 15 percentage points above Illinois, respectively. In grade 11, results were 42% in ELA, 32% in math, and 32% in science, trailing the state by 8, 8, and 16 points. Grade 9 results were closer to state rates: ELA was 1 point lower, math 7 points higher, and science 1 point lower. Other measures are favorable: the 2025–2026 graduation rate was 93%, 3 points above Illinois, and chronic absenteeism was 15%, 9 points below the state.
Results changed unevenly from 2024–2025 to 2025–2026: grade 10 rose by 28 points in ELA, 13 in math, and 32 in science, while grade 11 fell by 6, 9, and 13 points, respectively; grade 9 also declined in all three subjects, including a 17-point drop in science. SchoolDigger gives Sullivan 3 stars and ranks it 237th of 620 Illinois high schools, in the 62nd percentile; its rank position improved from 261st of 697 in 2023–2024, though its percentile slipped from 63. The school’s student-teacher ratio was 14.9:1 in 2024–2025, and 44% of students were free/reduced lunch eligible that year. With only one school in the area, these figures cannot show how Sullivan compares with local peers.
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