<p>Each school’s common data set section I.3 gives a fairly detailed breakdown of classes by size. With very few exceptions–far fewer than is commonly realized—students at research universities will on average spend a LOT more time in large classes than students at LACs. </p>
<p>Here’s the breakdown from the common data sets for a leading LAC (Haverford), a leading private research university (Princeton), and a leading public university (UCLA)</p>
<p>LAC: Haverford
Class size: # of classes (% of total)
2-9: 114 (34.2%)
10-19: 143 (42.9%)
20-29: 47 (14.1%)
30-39: 22 (6.6%)
40-49: 6 (1.8%)
50-99: 1 (0.3%)
100+: 0 (0%)
Total 333 </p>
<p>Private research university: Princeton
Class size: # of classes (% of total)
2-9: 226 (27.0%)
10-19: 370 (44.3%)
20-29: 87 (10.4%)
30-39: 37 (4.4%)
40-49: 22 (2.6%)
50-99: 56 (6.7%)
100+: 38 (4.5%)
Total 836</p>
<p>Public research university: UCLA
Class size: # of classes (% of total)
2-9: 469 (23.3%)
10-19: 553 (27.5%)
20-29: 333 (16.6%)
30-39: 131 (6.5%)
40-49: 84 (4.2%)
50-99: 208 (10.4%)
100+: 231 (11.5%)
Total 2,009</p>
<p>Now notice that Haverford and Princeton look pretty similar in percentage of small classes: 77.1% of the classes at Haverford have fewer than 20 students, while at Princeton 71.3% are in that “small” size range. But look at the other end of the scale: Haverford has only 1 class with 50+ students, or 0.3% of the total, while 11.2% of Princeton’s classes are in that “large” size range. Here’s the part that’s often overlooked: It’s not so much the number of small classes, but the number of large classes that determines what fraction of their time students spend in large classes. Each small class is, by definition, small, serving only a few students, while each big class has, by definition, many students registered for it. It takes more than 5 small classes (<20) to equal the number of students registered for a single class of 100+. So if a school has, say, 6 times as many small classes as large ones, that doesn’t mean students are spending 6 times as much time in small classes as large ones; it probably means they’re spending roughly equal amounts of time in large as in small classes, because there are so many more students enrolled in each large class. I won’t bore you with the math, but if you assume that the size of the average class in each size range is the mid-point of that range, and if you further assume that the average class of 100+ has 125 students, you get the following:</p>
<p>% of student time spent in small classes (< 20):
Haverford 55.3%
Princeton 34.0%
UCLA 15.4%</p>
<p>% of student time spend in large classes (50+):
Haverford 1.5%
Princeton 44.1%
UCLA 61.5%</p>
<p>Notice that Princeton students are actually spending more time in large classes (50+) than in small ones (<20). Princeton students spend nearly half their time in large classes; Haverford students almost none. Of course, students at the public university, UCLA, spend even more time in large classes and relatively little in small ones, but to my mind, at least, the difference between Haverford and Princeton on this score is even more striking than the difference between Princeton and UCLA. If you want small classes, attend a LAC, not a research university. (There are a handful of exceptions).</p>