WILLIAM SIDNEY MOUNT ELEMENTARY SCHOOL

WILLIAM SIDNEY MOUNT ELEMENTARY SCHOOL is a reasonably sized primary school in STONY BROOK, New York, overseen by THREE VILLAGE CENTRAL SCHOOL DISTRICT. The school instructs 525 students in grades pre-K through 6.

THREE VILLAGE CENTRAL SCHOOL DISTRICT comprises 8 schools with combined enrollment of 5,629 students; WILLIAM SIDNEY MOUNT ELEMENTARY SCHOOL is among them.

Demographically, WILLIAM SIDNEY MOUNT ELEMENTARY SCHOOL shows that 55% of the student body identifies as White; the rest comes out to 24% Asian, 14% Hispanic, 5% multiracial. That is meaningfully less White than the county at large, where the share is closer to 66%.

On the resource side, On paper, WILLIAM SIDNEY MOUNT ELEMENTARY SCHOOL has 40 full-time-equivalent teachers, translating to a class-load average of around 13.1:1. That tracks the state average closely. About 20% of enrolled students meet the income threshold for free or reduced-price lunch, a commonly cited indicator of low-income enrollment. That share is below Suffolk County's rate of about 39%.

On a residual basis (actual vs predicted given the student mix), WILLIAM SIDNEY MOUNT ELEMENTARY SCHOOL tracks the demographic baseline. The model predicts 67.5% given the school's FRL share; actual proficiency is 61.0%.

In the surrounding community, ACS estimates for Suffolk County put median household earnings sit near $130,686, roughly 40% of adults have completed at least a four-year degree, and the poverty rate sits near 4%. Across Suffolk County's 343 public schools (combined enrollment of about 222,439 students), WILLIAM SIDNEY MOUNT ELEMENTARY SCHOOL is one campus in the mix.

ROBERT CUSHMAN MURPHY JUNIOR HIGH SCHOOL is the nearest neighboring public school, about 1.2 miles from this campus. Counting just inside five miles, 8 other public schools cluster around WILLIAM SIDNEY MOUNT ELEMENTARY SCHOOL. On composite proficiency, WILLIAM SIDNEY MOUNT ELEMENTARY SCHOOL comes 7th of 9 in the immediate cluster, behind the nearby-schools average of 65.6%.

The campus sits in a bedroom-community setting.

Trend over the last 7 years. Over the past 7-year window, the student count increased 10%: 476 students in 2018 compared to 525 in 2025. Over the same period, the White share declined from 71% to 55%. Class-load math has pulled in: from 14.9:1 in 2018 to 13.1:1 in 2025.

Within the allk12 community for this school, recent activity here tends to focus on school events, parent volunteer needs, and clubs. Members of the school community can share what they know.