In order to study the new curriculum, as well as to help teachers understand new textbooks well, the authors make horizontal comparisons between Editions A and B of Experimental Mathematics (2) textbook in ordinary senior high schools (Grades 10-12) of PEP Edition, which focuses on the topic of line slope. The interview was made with 11 selected teachers who are teaching the content in the light of Edition B. It was found that there are obvious differences in the introduction of concepts and the exercises. The interviews showed that teachers were familiar to the contents of Edition A and saw it reasonable, because few differences are found between Edition A and the old Edition. The teachers also viewed that though the contents of Edition B were easy and fit to self-educated, but its reasoning is not clear, and the examples are not enough so that the teachers need to add additional examples.