Complex sentence: He states that his findings show no systematic relationship between the amount of money spent in an American school and the amount of student learning in a given district, and therefore he generally opposes increases in school funding to achieve overall reductions in class size, for example.
Split into simpler sentences: He states that his findings show no systematic relationship between the amount of money spent in an American school and the amount of student learning in a given district. Because of this, he generally opposes increases in school funding for overall reductions in class size, for example.