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Alumni: what's one memory from Crystal Lake South High School that still sticks with you?
Community prompt from u/allk12. Replies below.
Enrollment
1,279
High
DISTRICT 1,301 · STATE 834
SCHOOL COMMUNITY·CHSD 155·NCES 171137001368
Crystal Lake South High School
1200 S McHenry Ave, Crystal Lake, IL 60014 · (815) 455-3860 · McHenry County
GRADES 09–12HIGH21-SUBURBREGULAR SCHOOL1,279 STUDENTS
B+
allk12 Grade
Scored higher than 70% of Illinois public high schools
- A-Test scores Share of students meeting the state standard in reading, math, and other tested subjects, 2023-24 and 2024-25.
- BBeats expectations How far test scores land above or below what the share of low-income students predicts for a school in this state.
- ·Three-year trend Not available for this school, so the grade uses the other parts.
Grades compare a school only with schools in the same state, because every state gives its own test. How grades work · Top-graded Illinois public high schools
Student : Teacher
16.5:1
78 FTE teachers
DISTRICT 16.9:1 · STATE 13.8:1
Free / Reduced Lunch
32%
411 students
DISTRICT 29% · STATE 56%
Community
5
0 members
Enrollment and student:teacher ratio compared against other high schools. Free/Reduced Lunch and demographics compared against all schools.
Enrollment by grade, 2024-25
| Grade | Students | Share |
|---|---|---|
| Grade 9 | 311 | 24% |
| Grade 10 | 327 | 26% |
| Grade 11 | 305 | 24% |
| Grade 12 | 336 | 26% |
Student demographics
51%Diversity index
The chance that two students picked at random belong to different racial or ethnic groups.
DISTRICT 46% · STATE 69% · US 70%
Student head counts by race/ethnicity from federal NCES enrollment data. District, state, and US figures are each group's share of all public school students in that area (US excludes territories). Very small groups may be suppressed in the source, so categories do not always sum exactly to total enrollment.
Gender split
BeatsExpectations
Demographically-adjusted score · methodologyTier
AS EXPECTED
Performing as predicted given the school's student profile
Actual proficiency
46.5%
composite math + reading, all grades
Predicted
53.0%
based on IL schools with similar FRL share
Beats by
-6.4pp
below demographic expectation
What this means: About 47% of students here test proficient in math and reading, compared with the roughly 53% typical for Illinois schools with a similar share of low-income students. BeatsExpectations measures results against demographically similar schools rather than by raw scores, and this school falls within the typical range, neither among Illinois's top nor bottom 10%.
BeatsExpectations runs a per-state regression of proficiency on free/reduced-lunch share, then scores each school by residual. How this is calculated →
Schools most like Crystal Lake South High School
Crystal Lake South High School's state test result (46.5% proficient) is higher than 4 of the 5 schools below with a result.
| School | Students | Low-income | Proficient |
|---|---|---|---|
| Crystal Lake South High School this school | 1,279 | 32.1% | 46.5% |
| Crystal Lake Central High School Crystal Lake | 1,443 | 35.3% | 45.3% |
| Wauconda High School Wauconda | 1,452 | 35.5% | 44.4% |
| Wheaton Warrenville South High School Wheaton | 1,864 | 28.9% | 54.7% |
| Plainfield High School Plainfield | 1,800 | 34.7% | 40.6% |
| Hampshire High School Hampshire | 2,046 | 32.1% | 46.4% |
Matched among Illinois high schools on enrollment, the share of students from low-income families (eligible for free or reduced-price lunch), and racial and ethnic makeup. Proficient is the average share of students meeting the state standard across all of the school's state tests in 2023-24 and 2024-25, the same combined score our test-score rankings use. Online schools and schools serving specialized populations are not matched.
Where Crystal Lake South High School ranks
Among high schools| Measure | This school | In Illinois | In McHenry County |
|---|---|---|---|
| State test proficiency ranked highest first | 46.5% | #113 of 573 | #5 of 13 |
| Enrollment ranked largest first | 1,279 | #177 of 708 | #6 of 14 |
| Students per teacher ranked fewest first | 16.5:1 | #435 of 528 | #11 of 13 |
| Diversity index ranked most diverse first | 51.0% | #174 of 537 | #4 of 13 |
| Free and reduced lunch ranked highest share first | 32.1% | #488 of 578 | #8 of 13 |
| Enrollment change since 2017-18 ranked steepest decline first | -12.5% | #126 of 358 | #5 of 10 |
Ranked against other public high schools. Online schools are left out of every list, and test-score lists leave out schools that serve specialized populations. Each rank links to the full list. Arrows under a test-score rank show places moved since the prior test year, among schools tested both years.
4-year change
SY 2020-21 vs SY 2024-25Enrollment
1,279
-131 (-9%) vs 2020
+7% since 1990-91, when it was 1,190
Source: NCES Common Core of Data
Enrollment and staffing by year
| School year | Students | Teachers (FTE) | Students per teacher | Free and reduced lunch |
|---|---|---|---|---|
| 2024-25 | 1,279 | 77.7 | 16.5:1 | 32% (411) |
| 2023-24 | 1,291 | 74.9 | 17.2:1 | 31% (395) |
| 2022-23 | 1,301 | 74 | 17.6:1 | 27% (347) |
| 2020-21 | 1,410 | N/A | N/A | N/A |
| 2017-18 | 1,462 | 82.6 | 17.7:1 | 19% (278) |
| 2015-16 | 1,686 | 94 | 17.9:1 | 15% (250) |
| 2010-11 | 1,934 | 109 | 17.7:1 | 8% (151) |
| 2000-01 | 1,384 | 78 | 17.7:1 | N/A |
| 1990-91 | 1,190 | 67 | 17.8:1 | N/A |
Source: NCES Common Core of Data. Rows are the federal collections on file for Crystal Lake South High School.
Since 2017-18: students down 13% (1,462 to 1,279); teachers down 6% (82.6 to 77.7).
About Crystal Lake South High School
Crystal Lake South High School is a public high school run by CHSD 155 in Crystal Lake, Illinois. It enrolled 1,279 students in grades 9 through 12 for the 2024-25 school year. Statewide, high schools in Illinois average about 834 students each.
Federal data list 4 schools in CHSD 155, with 5,203 students enrolled.
Crystal Lake South High School's enrollment is 65% White. Enrollment also includes 26% Hispanic, 4% Asian, 3% Black, and 2% multiracial. Among people living in McHenry County, the White share is about 80%. The chance that two students picked at random at Crystal Lake South High School belong to different racial or ethnic groups, known as the diversity index, is 51%.
The school reported 77.7 full-time-equivalent teachers in 2024-25 and a ratio of 16.5:1. The 13.8:1 average for high schools in Illinois is lower than this school's figure. Eligible students account for 32% of enrollment in the free or reduced-price lunch program.
Measured against Illinois public high schools, Crystal Lake South High School receives a B+. The grade weighs proficiency most heavily, then how results compare with what the school's low-income share predicts, then the three-year change.
Test results at Crystal Lake South High School are 6.4 points below what its free or reduced-price lunch share predicts (46.5% actual, 53.0% predicted).
McHenry County has about 312,591 residents, and median household income is about $104,802, 35% of adults hold a bachelor's degree or higher, and about 4% of people live in poverty. The public schools of McHenry County number 89 and enroll about 50,123.
The school nearest to Crystal Lake South High School is Coventry Elementary School, at a distance of about 0.8 miles. Counting only straight-line distance, at least 8 other public schools are within five miles. Of the 9 nearby schools with scores, including this one, Crystal Lake South High School is 5th on average proficiency.
Crystal Lake South High School falls in the Suburb: Large locale category, used for schools in a suburban area outside a principal city, within an urbanized area with a population of 250,000 or more.
Enrollment was 1,410 in 2020-21 and 1,279 in 2024-25, a decrease of 131 students.
Discussion on this page can cover school safety, transportation, and start times. Reviews and ratings from people who know the school are welcome.
McHenry County at a glance
View full county profilePopulation
312,591
Census ACS
Median income
$104,802
Household, ACS
Bachelor's+
35%
Adults 25+
Poverty rate
4%
Below federal line
Schools in county
89
50,123 students
Quick facts
Related schools
Other schools in CHSD 155
- Crystal Lake Central High SchoolHigh · 1,443 students
- Cary-Grove Community High SchoolHigh · 1,348 students
- Prairie Ridge High SchoolHigh · 1,133 students
- Haber Oaks CampusHigh
Other schools in Crystal Lake
- Crystal Lake Central High SchoolHigh · 1,443 students
- Prairie Ridge High SchoolHigh · 1,133 students
- Hannah Beardsley Middle SchoolMiddle · 829 students
- Lundahl Middle SchoolMiddle · 797 students
- Richard F Bernotas Middle SchoolMiddle · 737 students
- North Elementary SchoolElementary · 638 students
Nearby schools
- Coventry Elementary School0.8 mi · 629
- Lundahl Middle School1.0 mi · 797
- Canterbury Elementary School1.1 mi · 486
- South Elementary School1.2 mi · 390
- Indian Prairie Elementary School1.3 mi · 496
- Woods Creek Elementary School1.3 mi · 489
Frequently asked questions
About Crystal Lake South High SchoolHow large is Crystal Lake South High School?
Crystal Lake South High School enrolls approximately 1,279 students in grades 09-12.
Is Crystal Lake South High School an elementary, middle, or high school?
Crystal Lake South High School is a high school covering grades 09-12.
What is the student-teacher ratio at Crystal Lake South High School?
The student-to-teacher ratio at Crystal Lake South High School is approximately 16.5:1 (78 FTE teachers).
What is the racial breakdown of students at Crystal Lake South High School?
At Crystal Lake South High School, the student body is approximately 65% White, 26% Hispanic, 3% Black, 4% Asian, 2% Two or more.
Who oversees Crystal Lake South High School?
Crystal Lake South High School is overseen by CHSD 155 in McHenry County.
Data sourceSchool profile facts are sourced from the NCES. Community content is posted by allk12 members.