During the 2009–10 school year, there were a total of 10,979 pupils attending classes in Bern. There were 89 kindergarten classes with a total of 1,641 pupils in the municipality. Of the kindergarten pupils, 32.4% were permanent or temporary residents of Switzerland (not citizens) and 40.2% have a different mother language than the classroom language. The municipality had 266 primary classes and 5,040 pupils. Of the primary pupils, 30.1% were permanent or temporary residents of Switzerland (not citizens) and 35.7% have a different mother language than the classroom language. During the same year, there were 151 lower secondary classes with a total of 2,581 pupils. There were 28.7% who were permanent or temporary residents of Switzerland (not citizens) and 32.7% have a different mother language than the classroom language.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): How many lower secondary classes were there?
151