How does Los Osos High compare to other high schools in Rancho Cucamonga?

Los Osos High has a SchoolScope composite score of 68.4/100, placing it at the 89th percentile statewide. 39% of students exceed standard, with a total of 1,245 students tested across grades and subjects.

What percentage of students exceed standards at Los Osos High?

39.5% of students at Los Osos High exceed the state standard on CAASPP assessments, while 65.0% meet or exceed it. The gap between these two numbers reveals whether the school pushes students beyond basic proficiency.

What is the chronic absenteeism rate at Los Osos High?

25.0% of students at Los Osos High are chronically absent (missing 10% or more of school days). This metric reflects school culture and family engagement, and is weighted at 15% in our composite score.

Los Osos High

High School

Chaffey Joint Union High Rancho CucamongaSan Bernardino County91737

Composite Score

out of 100

State Percentile

of high schools

State Rank

of 1,739 California high schools

School overview

Enrollment

2,759 students

Student-Teacher Ratio

25:1

Free/Reduced Lunch

34%

Teachers

110 full-time

College & career readiness

Graduation Rate

96.3%

AP Exam Prepared

65.4%

A-G Completion

77.8%

College-Going Rate

81.4%

Data source: California Department of Education — ACGR, CCI, CGR reports

Dashboard indicators

ELA Year-over-Year

Maintained

+0.5 pts DFS change

Math Year-over-Year

Maintained

+0.9 pts DFS change

EL Proficiency (ELPAC)

21.3%

English learners at Level 4 (Well Developed) · 61 tested

Data source: California School Dashboard 2025, ELPAC 2024

Student demographics

Hispanic40.7%

White27.2%

Asian18.6%

Black6.0%

Other7.6%

Performance breakdown

Performance breakdown for Los Osos High
Category	Percentage
Exceeded Standard	39.5%
Met Standard	25.5%
Below Standard	35.0%

What other rankings don't show you

Most rating sites report "65% proficient" for Los Osos High and stop there. Here's what that number hides:

39.5% of students exceeded standard while 25.5% merely met it. That exceeded rate is 24.0 points above the state average of 15.5%. That's 14.6 points above the Chaffey Joint Union High district average of 24.9%. Compared to the 1 nearby schools within ~3 miles, this exceeded rate is 6.3 points higher (vs 33.2% average). The gap between "met" and "exceeded" is the difference between a school that clears the bar and one that raises it.

The graduation rate is 96.3% — above the state target. 77.8% of students complete A-G requirements for UC/CSU eligibility — a strong college readiness signal. 81.4% of graduates go on to college within a year.

Chronic absenteeism is 25.0%, better than the state average of 34.0%.

Why the exceeded vs. met split matters →