Concentric model a makes instruction a subsystem of curriculum, which is itself a sub system of the whole system of education. Concentric model B subsumes curriculum within the subsystem instruction. A clear hierarchical relationship comes through in both these models. Curriculum ranks above instruction in model A and instruction is predominant in model B. in model A instruction is a very dependent portion of the entity curriculum. Model B makes curriculum subservient to and derivative from the more global instruction.