CRA has its roots in the work of Bruner and Kenney (1965), who defined learning through “Stages of Representation:”
Enactive, or learning through movement and action
Iconic, or learning through pictures
Symbolic, or learning through abstract symbols
The CRA instructional sequence/ approach provides a graduated, conceptually supported line of work to create meaningful connections among concrete, representational, and abstract levels of understanding. CRA is an intervention for mathematics instruction that research suggests can enhance the mathematics performance of students in a classroom. It is a three-stage learning process where students learn through physical manipulation of concrete objects, followed by learning through pictorial representations of the concrete manipulations, and ending with solving problems using abstract notation.