Summary:
ZIP code 98040 has one middle school, Islander Middle School, serving grades 6–8 in the Mercer Island community, with about 960 students.
Islander Middle School is a particularly strong option for families seeking high academic performance. It ranked 9th out of 514 Washington schools in 2025–2026, placing it in the state’s 98th percentile, and it has received a five-star rating. The school’s ranking has improved steadily, from 19th in 2023–2024 to 13th the following year and then 9th most recently. In 2025–2026, proficiency was 84.24% in English language arts, 78.84% in math, and 75.45% in science. These results were dramatically higher than Washington averages—by 31.43 points in English, 35.73 points in math, and 24.50 points in science.
The school is part of the highly rated Mercer Island School District, ranked first among 238 Washington districts. Islander’s English and math results were slightly below district averages, while science was 8.78 percentage points lower, making science the clearest area to watch despite strong statewide performance. Seventh grade was the strongest grade in both English language arts, at 87.19%, and math, at 82.98%; eighth-grade results were somewhat lower in both subjects. The school improved year over year in all three tested subjects. Other context includes a 21.3-to-1 student-teacher ratio, $17,200 in reported per-student spending, and 7.81% participation in free or reduced-price lunch programs.
Thank you for your feedback!