Summary
Islander Middle School is a public school serving approximately 960 students in grades 6–8 in Mercer Island, a suburban community near Seattle, and is part of the Mercer Island School District. It is one of Washington’s highest-performing middle schools, ranking 9th out of 514 schools statewide for 2025–26, in the 98th percentile, with a five-star rating. Its statewide rank has remained between 9th and 19th in every reported year since 2016–17, indicating sustained achievement rather than a one-year result.
Academic results are strong across all tested subjects: 84.24% of students are proficient in English language arts, 78.84% in math, and 75.45% in science. These rates are substantially above Washington averages of 52.81%, 43.11%, and 50.95%, respectively. Results have also improved since 2023–24, with gains of 5.05 percentage points in ELA, 6.25 points in math, and 6.06 points in science. Seventh grade is the strongest overall, although every reported grade-subject result is above 75%. Science is the clearest area for continued attention because it trails the district result by 8.78 points, while math is the main area where the school trails nearby Tyee Middle School.
Among nearby schools, Tyee Middle School is the closest academic comparison, ranking 7th statewide and slightly exceeding Islander in math and science; Islander is about 1 point higher in ELA. Islander substantially outperforms Rainier Prep and most other schools in the comparison group. Its 7.81% free/reduced-price lunch rate is also much lower than rates reported by many nearby schools, so proficiency comparisons should be viewed in context. Even so, statewide comparative rankings are especially strong for low-socioeconomic-status students, Hispanic students, and students receiving special education services. Spending was $17,200 per student, and the student-teacher ratio was 21.3:1, showing that the school’s high performance is not paired with the lowest ratio or highest spending among nearby schools.
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