What caused the decline of Alief and the deterioration of the school district?

I am now a college student. Before college, I went to high school in Elsik, Alief ISD for 9th grade, and then because I couldn't stand the atmosphere at that school – most of the students were noisy and didn't pay attention in class, the teachers were good, but they couldn't handle the students in their classes (at least in the 9th-grade center), also my mother had a job change, I went to Fort bend ISD. Yes, although the pressure to study has become greater, my new high school is indeed better.

A few years ago I was working part-time in a restaurant at Sugar Land, there was an older gentleman who came to dinner often at the restaurant I was working at, he was very talkative. One time we got to talking about school and he was surprised that I came from the Alief School District, and then he said, somewhat ruefully, "30 years ago, that area of Alief was not that bad. "

What caused the decline of Alief and the deterioration of the school district? When I went to school in Elsik I bet the teachers I had were great, but it's a real shame that no one listened in class.