Cornerstone Montessori School
Montessori school · Grades Pre-K–6
Sumner, WA
1644 Gault St, Sumner, WA 98390
Overall grade: A-
ChooseAPrivateSchool.com grade, from official facts compared with similar schools.
- A-Class size
- B+Years serving families
What stands out
- Smaller classes than 62% of Montessori schools in Washington
In Sumner, Washington, Cornerstone Montessori School is a Montessori school for students from pre-K through 6th grade. About 41 students attend, with roughly 6 students per teacher, smaller classes than 62% of Montessori elementary schools in Washington. Enrollment is up about 1267% since 2011–12. The school day runs about 6 hours, 180 days a year.
At a glance
- Grades
- Grades Pre-K–6
- Students
- 41
- Teachers
- 6.9 (full-time equivalent)
- Students per teacher
- 5.9
- Boys and girls
- Coed · 15 girls, 26 boys
- Religious affiliation
- None (nonsectarian)
- Program
- Montessori
- School day
- About 6 hours
- School year
- 180 days
- Library
- Yes
Reviews
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How it compares
- Smaller classes than 62% of Montessori elementary schools in Washington (6 students per teacher).
- A smaller school: fewer students than 59% of Montessori elementary schools in Washington.
- Compared with 34 Montessori elementary schools in Washington.
Students by survey year
Total students reported in official records since 2011–12.
Students by grade
Student body
Questions to ask on a tour
- What is tuition, and what does it include (books, fees, uniforms, trips)?
- Do you offer financial aid, sibling discounts or payment plans?
- Do you accept ESA, voucher or tax-credit scholarship funds?
- How big are classes in my child's grade?
- What support is there for students who need extra help or more challenge?
- Is the school accredited, and by whom?
- What do a typical day and a typical week look like?
- How does the school communicate with families?
Questions about Cornerstone Montessori School
What grades does Cornerstone Montessori School serve?
Cornerstone Montessori School serves grades Pre-K–6.
How many students attend Cornerstone Montessori School?
About 41 students, with 6 students per teacher, according to official records.
How much is tuition at Cornerstone Montessori School?
Call the school to ask about tuition, financial aid and payment plans.
Official record · Updated October 2026 · Official search · Something wrong? Tell us
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