Hello. Can i ask couple of things about ACL?

College student here.
Im exploring in packet tracer about ACL. Some basic stuff about standard and extended. Ive created some sort of a computer lab classroom scenario with a data center in which only the teacher's pc may access through the data center. My one network(classroom) is dedicated for standard acl in which i have no problem in blocking the necessary pcs to data network pc and on another classroom for extended. They were being connected in one router and that router has been routed to the network dedicated for data center. My problem is that the network(has 4 PCs) for extended has been denied in the data center even though i only blocked one. "access-list 101 deny ip x.x.x.x x.x.x.x(ip of the pc) x.x.x.x x.x.x.x(ip of the destination)" and ive also wrote the "ip access-list 101 in" in the nearest interface in my source.

May i ask what seems to be the problem?
PS: sorry for my bad english