The brief
A private elementary school in Sumner, WA serving grades Pre-K – 6th.
It ranks 172 of 420 schools in Washington.
Cornerstone Montessori School is a private school: it enrolls by application and tuition, and its rating comes from the private-school model, which is not comparable with a public rating.
About this school's datarating: low confidence · 3 sources, 2019–2024
Every number on this page comes from a published source with a stated period. Where a source is partial, aging, an estimate, or describes a surrounding area rather than the school, that limitation is named here.
- Estimated academic score. This school does not have standardized test data. Based on WA statewide data. Learn more
- What this rating measures: classroom size, instructional time, student diversity, community resources, and school characteristics. Private schools are ranked against other private schools in WA.
- Component weights adjusted due to data availability.
Score basis: private school model. Data coverage: 80% of scoring components had data. Components scored: 4 of 5. Ranking pool: private schools in WA.
- School directory (enrollment, grades, staff, contact)
- NCES Private School Universe Survey (PSS) · SY 2023–24 · Low confidence
- Vintage not available. Do not use this measure alone.
- MySchoolScout rating and rank
- MySchoolScout ranking model · Low confidence
- Vintage not available. Do not use this measure alone.
- Available for part of the eligible units; results may not represent the full area.
- Derived as a weighted blend of the component scores shown in Academics from state assessment, EdFacts growth, and NCES resource records.
- Neighborhood (income, housing, education)
- U.S. Census ACS 5-year estimates · ACS 2019–2023 5-year estimates · Low confidence
- Older source: ACS 2019–2023 5-year estimates. Use as historical context.
- Reported for the ZCTA for ZIP 98390; this does not measure the attendance area.
Evidence periods: Rating mixed/unknown input periods; assessments vintage unavailable; directory SY 2023–24
The neighborhood
Where it sits, and what the area looks like.Open the Seattle school map to see school quality against home prices across the metro.
The area
- Median income
- $97,815
- Median home value
- $471,500
- Median rent
- $1,886/mo
- College educated
- 23%
- Homeownership
- 51.3%
- Poverty rate
- 6.9%
U.S. Census ACS 5-year estimates · ACS 2019–2023 5-year estimates for the ZCTA associated with school ZIP 98390; this is area context, not an attendance boundary.
Getting around
- Walk Score
- 34
- Car-Dependent
- Bike Score
- 51
- Bikeable
- City reported crime
- 2,385/100K
- Reported Part-1 offenses (violent + property + arson) per 100,000 residents, from the FBI Uniform Crime Reporting program for Sumner. This is a city-level reported-crime measure, not a school safety rating.
Walk, transit and bike scores by
FBI Uniform Crime Reporting · 2025 · city context (Sumner), not school-level safety or attendance eligibility. Source details
Source period: 2025. Freshness not available.
Programs and who goes here
What the campus offers, and who it enrolls.Who goes here
- Two or More44%
- White39%
- Asian7%
- Native American5%
- Hispanic3%
- Pacific Islander2%
Enrollment mix: NCES Private School Universe Survey (PSS).
Compare nearby
Grade-compatible schools using the same rating model.Distance is proximity only; it is not attendance eligibility.
Private · tuition: Potential private option; tuition and admission requirements have not been verified.
The record
What is on file, and where each number came from.Questions families ask
What grades does Cornerstone Montessori School serve?
Cornerstone Montessori School serves students in grades Pre-K through 6th.
How many students attend Cornerstone Montessori School?
Cornerstone Montessori School has an enrollment of approximately 41 students.
What is the student-teacher ratio at Cornerstone Montessori School?
The student-teacher ratio at Cornerstone Montessori School is 5.9:1. A lower ratio generally means more individual attention per student. The national average is approximately 11:1 for private schools.
How does Cornerstone Montessori School rank in WA?
Cornerstone Montessori School ranks #172 of 420 private schools in WA.
What is Cornerstone Montessori School's MySchoolScout rating?
Cornerstone Montessori School has a current MySchoolScout rating of 6.6 out of 10. This score combines the level-appropriate components shown in the rating breakdown; equity data is shown separately for context.
Is Cornerstone Montessori School a private school?
Yes, Cornerstone Montessori School is a private coeducational school with a Nonsectarian affiliation. Private schools are not required to participate in state standardized testing, so academic performance data may be limited compared to public schools.
Is Cornerstone Montessori School a religious school?
No, Cornerstone Montessori School is a nonsectarian (non-religious) private school.
School facts
- Grades
- Pre-K – 6th
- Enrollment
- 41
- Gender split
- 63% M / 37% F
- Student-teacher ratio
- 5.9:1
- Teachers (FTE)
- 7
- Type
- Private
- Coed status
- Coed
- Affiliation
- Nonsectarian
- School day
- 6 hours
- Days per year
- 180 days
- Setting
- Large Suburb
- County
- Pierce County
- Phone
- (253) 987-7239
- Area population (ZIP 98390)
- 11,497
- Area average commute
- 30.2 min
- Area median age
- 35.9
NCES Private School Universe Survey (PSS) (SY 2023–24).
Sources and official links
Keep exploring
Related reading
Data from NCES Common Core of Data, Washington Dept. of Education, and U.S. Census ACS for the 2023–24 school year. Rankings computed by MySchoolScout. See all data sources.