I want to reduce the size of the classrooms in this country. For one basic reason, so that students can get more one-on-one time with teachers. And the way to do that is first to recruit more teachers. I've a plan in my budget to recruit 100,000 new, highly qualified teachers and to help local school districts build new schools.
I do not want to reduce the physical size of the classroom, rather I want there to be fewer students in the classrooms.  
The context clearly illustrates that the agent wants to reduce the number of students in the classroom, not physically shrinking the space they learn in.  By redirecting the subject to the physical dimensions of the room, the AI is misdirected away from the subject.  
( z1 contrast :ARG1 ( z2 want :polarity - :ARG0 ( z3 i ) :ARG1 ( z4 reduce :ARG0 z3 :ARG1 ( z5 size :mod ( z6 physical ) :poss ( z7 classroom ) ) ) ) :ARG2 ( z8 want :ARG0 z3 :ARG1 ( z9 have-quant :ARG1 ( z10 person :ARG0-of ( z11 study ) :location z7 ) :ARG3 ( z12 less ) ) ) )