Enrollment
251
California · 2024-25 NCES data
Elementary school (grades K-5) · Diamond Bar, CA
Armstrong Elementary
Federal NCES profile for Armstrong Elementary, including enrollment, faculty, free-lunch eligibility, demographics, and resource indicators - Resource Investment Index 37/100.
2024-25 NCES dataElementary school (grades K-5)NCES 063132004836
👥 S:T ratio 28
🌟 Gifted program 70
🎓 Counselors 50
📋 Attendance 0
Scored 0–100 from federal NCES and CRDC indicators, resource allocation, not test scores. Full methodology →
The verdict
Armstrong Elementary earns 37/100 on the Resource Investment Index, with class sizes smaller than 79% of California schools.
- #2 of 7
- elementary schools in Diamond Bar · Resource Index
- 37
- Resource Index · Typical
- 17.9:1
- small classes for California
- 49.4%
- free-lunch eligible
Armstrong Elementary has class sizes smaller than 79% of California schools. Computed live against every California school reporting to NCES.
By Resource Investment Index, Armstrong Elementary ranks #2 of 7 elementary schools in Diamond Bar, CA.
School address
District: Pomona Unified · California
NCES ID 063132004836 Verify on NCES CCD record →
Teachers (FTE)
14.0
Federal CCD staff survey
Students per teacher
17.9:1
vs 21.5:1 California avg
-17% vs state
Free-lunch eligible
49.4%
vs 55.5% California avg
-11% vs state
Student-teacher ratio in context
How Armstrong Elementary compares with California and U.S. medians
What stands out at Armstrong Elementary
Armstrong Elementary is a mid-sized elementary school in Diamond Bar, California, enrolling 251 students.
Class sizes run a bit leaner than typical: 17.9:1 puts it in the smaller third of California schools by student-teacher ratio.
Economic need runs somewhat below the state's typical profile, with 49.4% of students eligible for free meals.
Enrollment of 251 puts it in the smaller third of California schools by headcount.
Its Resource Investment Index lands in the upper third of 9,998 scored California schools.
Against 652 statewide peers matched on enrollment and economic need, it ranks in the upper tier at #170.
Its student body is led by Hispanic or Latino (60%) and Asian (15%) (diversity index 60/100).
Counselor coverage runs a bit thin, about 251 students per counselor, somewhat past the ASCA-recommended 250:1 benchmark.
Chronic absenteeism is elevated: 47.0% of students missed 10% or more of school days (2021-22 Civil Rights Data Collection).
Its district draws 17.6% of revenue from federal sources, an above-typical federal share that tends to track a higher-need student population.
Among Diamond Bar's elementary schools, it stands alongside Evergreen Elementary (709 students): Armstrong Elementary is smaller than that campus by headcount and runs leaner classes (17.9:1 vs 25.3:1).
Pomona Unified also operates Garey High (1,567 students) and Diamond Ranch High (1,542 students) alongside Armstrong Elementary.
Sourced from NCES CCD, CRDC, and F-33 (federal records, not a quality verdict). How we source and compute this.
Source: National Center for Education Statistics Common Core of Data + CRDC + F-33 · 2024-25
How Armstrong Elementary compares
Armstrong Elementary on the metrics families compare, against California and U.S. means.
| Metric | This school | vs California | California avg | U.S. avg |
|---|---|---|---|---|
| Students per teacher | 17.9:1 | ▼ 17% | 21.5:1 | 15.7:1 |
| Free-lunch eligible | 49.4% | ▼ 11% | 55.5% | 51.7% |
| Enrollment | 251 | top 79% | - | - |
Source: NCES Common Core of Data School-level CCD + state/national means from Public School Universe · 2024-25
17.9:1
Leaner classes than 25% of US schools, heavier class loads than most.
251
Bigger than 25% of US schools by enrollment, mid-sized for the country.
Equity indicators (what these measure)
Economic need
49.4%
free-lunch eligible
- 11% below the California average of 55.5%
Above the 40% Title I schoolwide threshold; federal funds support the whole school, not individual students.
Staffing depth
17.9:1
students per teacher
- 17% below state mean
Top 21% in California - lower ratio than 79% of state schools
Between 16:1 and 20:1, squarely in the typical U.S. public-school staffing range.
Engagement
47.0%
chronically absent (missed 10%+ of school days)
At or above 20%, the commonly used threshold for "high" chronic absenteeism, signaling significant barriers to regular attendance.
Funding equity
$17,545
per pupil, district-wide
- above California avg of $16,509
Somewhat above the U.S. public-school average, reflecting higher local or state investment per enrolled student.
Support staff
Counselors1.0 FTE
Per 251 students, the combined health-and-guidance staffing load for this school.
Discipline context
0
in-school suspensions + 1 out-of-school
Suspension rate: 0.0 per 100 students. Combined in-school and out-of-school rate: 0.4 per 100 students. Reported via the Civil Rights Data Collection.
Overview
- Common Core of Data (June 2026): enrollment, staffing, and the student-teacher ratio above.
- Civil Rights Data Collection: discipline counts and program access (AP, gifted, special education).
- F-33 School District Finance Survey: the district-wide per-pupil spending figures below.
Three separate federal collections, each on its own reporting cadence - which is why this school's numbers line up on a consistent basis against every other school and state on this site, rather than mixing figures pulled from different survey years.
Student demographics
Hispanic or Latino 59.8%
Asian 14.7%
White 10.0%
Two or More 9.2%
African American 6.4%
Largest group: Hispanic or Latino at 59.8% of enrollment.
Student-body diversity index 59.8/100
Simpson diversity index - at 59.8, Armstrong Elementary is more mixed than the California school average of 46.0.
Programs
Gifted & talented Yes
Funding & spending
District-wide per-pupil expenditure for Pomona Unified, which includes Armstrong Elementary.
$17,545
Per student
+6%
vs California
Avg $16,509
+6%
vs U.S.
Avg $16,593
Revenue mix
Local 21.6%
State 60.9%
Federal 17.6%
Source: NCES F-33 School District Finance Survey District-level finance · FY 2021-22 Per-pupil expenditure reflects the district-wide average. Individual school budgets are not reported at the federal level.
How Armstrong Elementary Compares to District-Mates
| School | Enrollment | Economic Profile | Student-Teacher Ratio |
|---|---|---|---|
| Garey High | Larger | Higher economic need | Higher S:T ratio |
| Diamond Ranch High | Larger | Similar economic need | Higher S:T ratio |
| School of Extended Educational Options | Larger | Similar economic need | Higher S:T ratio |
| Pomona High | Larger | Higher economic need | Similar S:T ratio |
| Ganesha High | Larger | Higher economic need | Higher S:T ratio |
Comparisons are relative to Armstrong Elementary's own figures; each column derives from NCES Common Core of Data.
Other Schools in This District
- Enrollment
- 1,567
- Students per teacher
- 20.9:1
- Resource Index
- 34/100
- Enrollment
- 1,542
- Students per teacher
- 23.4:1
- Resource Index
- 36/100
- Enrollment
- 1,204
- Students per teacher
- 32.5:1
- Resource Index
- 43/100
- Enrollment
- 993
- Students per teacher
- 16.6:1
- Resource Index
- 37/100
- Enrollment
- 895
- Students per teacher
- 19.5:1
- Resource Index
- 35/100
Similar elementary schools in Diamond Bar
6 comparable elementary schools (grades K-5) serving the same city.
Evergreen Elementary
Standard public school
709 students 25.3:1 students per teacher
Quail Summit Elementary
Standard public school
696 students 27.8:1 students per teacher
Castle Rock Elementary
Standard public school
684 students 26.3:1 students per teacher
Maple Hill Elementary
Standard public school
556 students 27.8:1 students per teacher
Pantera Elementary
Standard public school
512 students 24.4:1 students per teacher
Golden Springs Elementary
Standard public school
388 students 24.3:1 students per teacher
Similar elementary schools statewide
Matched by enrollment size and by staffing ratio across all of California, not just this city - a different peer set than the local comparisons above.
Similar enrollment (~251 students)
Similar student-teacher ratio (~17.9:1)
Next steps
Verify locally before acting on Armstrong Elementary's federal record.
- Compare Armstrong Elementary against another school. Compare schools
- Pomona Unified's spending and staffing shape this school. District profile
- Confirm current enrollment and boundaries with the school. Choosing guide
Federal record (CCD 2024-25, CRDC 2021-22) - PlainSchools assigns no subjective rating; the composite quality score is a transparent, reproducible index computed from this cited federal data.
Frequently asked questions about Armstrong Elementary
How many students attend Armstrong Elementary?
Armstrong Elementary has 251 students enrolled. It is an elementary school in Diamond Bar, CA.
What is the student-teacher ratio at Armstrong Elementary?
The student-teacher ratio at Armstrong Elementary is 17.9:1, which is 17% lower than the California average of 21.5:1 and 14% higher than the national average of 15.7:1. Lower ratios generally mean more individual attention per student.
What percentage of students receive free lunch at Armstrong Elementary?
49.4% of students at Armstrong Elementary are eligible for free lunch, compared to the California average of 55.5%.
What is the racial and ethnic makeup of Armstrong Elementary?
The largest demographic group at Armstrong Elementary is Hispanic or Latino at 59.8% of enrollment, in Diamond Bar, CA. Its student body is more racially and ethnically mixed than most US schools, with a diversity index of 59.8/100.
What is the Resource Investment Index for Armstrong Elementary?
Armstrong Elementary has a Resource Investment Index of 37/100 (typical reported resources relative to schools nationally) based on 4 factors: student-teacher ratio, counselor availability, attendance rates. Not a test-score or academic measure (national median ~41/100, see methodology).
How does Armstrong Elementary rank among elementary schools in Diamond Bar?
By Resource Investment Index, Armstrong Elementary ranks #2 of 7 elementary schools in Diamond Bar, CA. This compares federal resource and staffing data among local peers; it is not a test-score or academic ranking. See all elementary schools in Diamond Bar on the city page.
Is Armstrong Elementary a good school?
Armstrong Elementary earns 37/100 on the Resource Investment Index, with class sizes smaller than 79% of California schools. This is a resource snapshot, not an academic rating; see the Resource Investment Index question above for what the number does and doesn't measure.
What other schools are in Pomona Unified?
Besides Armstrong Elementary, Pomona Unified also operates Garey High (1,567 students), Diamond Ranch High (1,542 students), and School of Extended Educational Options (1,204 students). See the Pomona Unified district page for the complete list.
Related tools
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, or report a data error. Data current as of June 2026.