Friday, January 4, 2008

School Size and Class Size in NYC

Do smaller schools in NYC have smaller classes? I took at look at the numbers for 9th grade English general education classes. Here's what I found:

  • Smaller schools, on average, have smaller classes. Students attending small schools in NYC (those with fewer than 500 students) attend schools with an average class size of 23.8. For schools with 500-2000 students, the average is 25.6; and for schools with more than 2000 students, the average is 28.0.

  • These averages conceal the fact that a much higher proportion of small schools have very small classes. 24% of small schools have average classes of 20 or fewer, while 7% of medium sized schools and 2% of large schools do.

  • Only 5% of small schools have average class sizes of 30 or more, while 10% of medium sized schools do and 27% of large schools do.

To anecdotally make points 2 and 3 above, International High School in the Bronx has an average class size of 12.2, while Francis Lewis High School in Queens has an average class size of 32.8. What a difference 20 kids makes.

What's also interesting is that there are small schools that have very large class sizes - for example, the two largest 9th grade class sizes are at relatively new small schools (East Bronx Academy for the Future, 34; Brooklyn Generation School, 38.5). Why? One hypothesis is that some small schools have been able to find ways to turn away (or to not be sent) over the counter students, while others have not. Perhaps some schools have been successful in raising additional funds to reduce class size. Other ideas are welcome here.

The last two days have only provided a cursory look at these data, and there's a lot more that could be done. If you have suggestions, please let me know.

Update: At Edwize, Leo Casey weighs in on the school size/class size relationship.


Rachel said...

All else being equal, you'd expect more variation in class size in small schools than larger schools. If you have 100 ninth graders to put into English classes and are aiming for an average class size of 28, your actual choices are 4 classes of 25 or 3 classes of 33.3. If you have 500 ninth graders, your choices are 17 classes of 29.4 or 18 classes of 28.8. So the individual large classes in small schools could be schedule quirks.

Gideon said...

Might these average class size numbers be masking important differences between schools, specifically how class sizes are allocated among subjects, grade levels, experience of teachers, etc. For instance, it might be more important to have smaller class sizes in lower grades. Or a large band class along with small ELA classes.

EduDiva said...

In St. Louis county the class size would have no correlation to school size (I haven't run the numbers) but district finances. Maybe NYC would be more like the St. Louis city in this case. (I still don't want to run the numbers. Sigh.)

What implications do your numbers give?

I think smaller schools tend to provide fewer options. Is that really the case? If so, how would that be compared to the slightly smaller class size you found?

Where is the optimum size point? Would that vary for each community?

We have a large outer suburban district that has obviously found what it believes is its optimum size for elementary schools as each one is almost the exact same size. (Most districts here don't have that option.)

Leonie Haimson said...

The most important determinant of class size in NYC is how many students are sent to schools by Tweed per unit of space; and despite the claim by DOE that all schools have equal ability to reduce class size, this is not true, because different schools have very different levels of overcrowding as a result.

Tweed makes deals with certain small schools, allowing them to cap class sizes at much lower levels than the large "zoned" high schools.

Supposedly the pressure has risen on the small schools to take more students; it would be interesting to see how the averages have evolved in existing schools over time and in different cohorts of the small schools. In the national assessments of the Gates-funded small schools, many saw their original class size grow and this very significantly eroded their ability to succeed in providing individualized instruction to their students, according to the staff at these schools.

There are lots of error in the data though -- which would tend to bring the reported average class sizes significantly below where they really are in both types of schools.