- Enrollment
- 1,442
- Students per teacher
- 10.3:1
- Resource Index
- 61/100
Other / mixed grade configuration · Stony Brook, NY
William Sidney Mount Elementary School
Federal NCES profile for William Sidney Mount Elementary School, including enrollment, faculty, free-lunch eligibility, demographics, and resource indicators - Resource Investment Index 53/100.
2024-25 NCES dataOther / mixed grade configurationNCES 362820003810
👥 S:T ratio 49
🌟 Gifted program 30
📋 Attendance 80
Scored 0–100 from federal NCES and CRDC indicators, resource allocation, not test scores. Full methodology →
The verdict
William Sidney Mount Elementary School earns 53/100 on the Resource Investment Index, with class sizes near the New York median.
- 53
- Resource Index · Higher
- 12.8:1
- students per teacher
- 16.6%
- free-lunch eligible
- 525
- students enrolled
William Sidney Mount Elementary School has class sizes near the New York median. Computed live against every New York school reporting to NCES.
School address
District: Three Village Central School District · New York
NCES ID 362820003810 Verify on NCES CCD record →
NCES CCD universe card
School universe 362820003810 · Stony Brook, NY Other · MID · TRAD
525 enr · 12.8:1 · 16.6% lunch · RII 53
Nearest enrollment peer: Ward Melville Senior High School (1,442 students)
William Sidney Mount Elementary School CCD stamps from the federal school universe. NCES Common Core of Data stamps for this campus. Read with this school → · District book → · New York schools → · Find another →
William Sidney Mount Elementary School in the enrollment neighbourhood
Fall enrollment among this campus and nearest district peers
- Ward Melville
Ward Melville Senior High School
1,442 students
- Robert Cushman
Robert Cushman Murphy Junior High School
655 students
- Paul J Gelinas
Paul J Gelinas Junior High School
651 students
- Minnesauke Ele
Minnesauke Elementary School
644 students
- Setauket Eleme
Setauket Elementary School
599 students
- This school 525
William Sidney Mount Elementary School
525 students
What this shows William Sidney Mount Elementary School reports 525 students on the CCD universe file.
How William Sidney Mount Elementary School compares
William Sidney Mount Elementary School on the metrics families compare, against New York and U.S. means.
| Metric | This school | vs New York | New York avg | U.S. avg |
|---|---|---|---|---|
| Students per teacher | 12.8:1 | ▲ 8% | 11.8:1 | 15.7:1 |
| Free-lunch eligible | 16.6% | ▼ 70% | 56.2% | 51.7% |
| Enrollment | 525 | top 34% | - | - |
Source: NCES Common Core of Data School-level CCD + state/national means from Public School Universe · 2024-25
12.8:1
Leaner classes than 68% of US schools, among the more generously staffed nationally.
525
Bigger than 65% of US schools by enrollment, mid-sized for the country.
Equity indicators (what these measure)
Economic need
16.6%
free-lunch eligible
- 70% below the New York average of 56.2%
Below the 40% Title I threshold, among the lower-need profiles in the state; federal aid targets individual qualifying students rather than schoolwide programs.
Staffing depth
12.8:1
students per teacher
- 8% above state mean
Top 69% in New York - lower ratio than 31% of state schools
Well under the widely cited 15:1 individualized-attention benchmark, among the leaner class loads nationally.
Engagement
8.0%
chronically absent (missed 10%+ of school days)
In the 5-10% range, close to the pre-pandemic national baseline.
Funding equity
$36,733
per pupil, district-wide
- above New York avg of $28,120
Well above the U.S. public-school average, reflecting substantially higher local or state investment per enrolled student.
Support staff
Counselors0.0 FTE
Student-support staffing from the Civil Rights Data Collection.
Discipline context
2
in-school suspensions + 0 out-of-school
Suspension rate: 0.4 per 100 students. Combined in-school and out-of-school rate: 0.4 per 100 students. Reported via the Civil Rights Data Collection.
Student demographics
White 55.0%
Asian 24.4%
Hispanic or Latino 14.1%
Two or More 5.3%
African American 1.1%
Largest group: White at 55.0% of enrollment.
Student-body diversity index 61.5/100
Simpson diversity index - at 61.5, William Sidney Mount Elementary School is more mixed than the New York school average of 45.5.
Programs
Funding & spending
District-wide per-pupil expenditure for Three Village Central School District, which includes William Sidney Mount Elementary School.
$36,733
Per student
+31%
vs New York
Avg $28,120
+108%
vs U.S.
Avg $17,658
Revenue mix
Local 71.7%
State 25.5%
Federal 2.8%
Source: NCES F-33 School District Finance Survey District-level finance · FY 2022-23 Per-pupil expenditure reflects the district-wide average. Individual school budgets are not reported at the federal level.
How William Sidney Mount Elementary School Compares to District-Mates
| School | Enrollment | Economic Profile | Student-Teacher Ratio |
|---|---|---|---|
| Ward Melville Senior High School | Larger | Similar economic need | Lower S:T ratio |
| Robert Cushman Murphy Junior High School | Similar size | Similar economic need | Lower S:T ratio |
| Paul J Gelinas Junior High School | Similar size | Similar economic need | Lower S:T ratio |
| Minnesauke Elementary School | Similar size | Similar economic need | Similar S:T ratio |
| Setauket Elementary School | Similar size | Similar economic need | Similar S:T ratio |
Comparisons are relative to William Sidney Mount Elementary School's own figures; each column derives from NCES Common Core of Data.
Other Schools in This District
- Enrollment
- 655
- Students per teacher
- 10.2:1
- Resource Index
- 57/100
- Enrollment
- 651
- Students per teacher
- 10.8:1
- Resource Index
- 60/100
- Enrollment
- 644
- Students per teacher
- 14:1
- Resource Index
- 51/100
- Enrollment
- 599
- Students per teacher
- 11.7:1
- Resource Index
- 55/100
Nationwide other schools with similar size or staffing
Out-of-state peers matched by enrollment and by student-teacher ratio, not the same-city or same-district lists above.
Similar enrollment (~525 students)
Frequently asked questions about William Sidney Mount Elementary School
How many students attend William Sidney Mount Elementary School?
William Sidney Mount Elementary School has 525 students enrolled. It is a public school in Stony Brook, NY.
What is the student-teacher ratio at William Sidney Mount Elementary School?
The student-teacher ratio at William Sidney Mount Elementary School is 12.8:1, which is 8% higher than the New York average of 11.8:1 and 18% lower than the national average of 15.7:1.
What percentage of students receive free lunch at William Sidney Mount Elementary School?
16.6% of students at William Sidney Mount Elementary School are eligible for free lunch, compared to the New York average of 56.2%.
What is the racial and ethnic makeup of William Sidney Mount Elementary School?
The largest demographic group at William Sidney Mount Elementary School is White at 55.0% of enrollment, in Stony Brook, NY. Its student body is more racially and ethnically mixed than most US schools, with a diversity index of 61.5/100.
What is the Resource Investment Index for William Sidney Mount Elementary School?
William Sidney Mount Elementary School has a Resource Investment Index of 53/100 (higher reported resources relative to schools nationally) based on 3 factors: student-teacher ratio, gifted-program reporting, chronic absenteeism. Not a test-score or academic measure (national median ~41/100, see methodology).
What other schools are in Three Village Central School District?
Besides William Sidney Mount Elementary School, Three Village Central School District also operates Ward Melville Senior High School (1,442 students), Robert Cushman Murphy Junior High School (655 students), and Paul J Gelinas Junior High School (651 students). See the Three Village Central School District district page for the complete list.
Every figure on PlainSchools is rendered directly from the source NCES, CRDC and F-33 federal records, no number is typed in by an editor. Each school's figures reflect its most recent NCES/CRDC submission on file. See our editorial standards & corrections policy, the methodology behind these numbers, the data changelog, or report a data error. Data current as of August 2026.