the process in which a child can pair two or more objects, one for one For example, a learner has a group of pencils, and a group of rocks, and puts one pencils with each rock If there are no pencils left over when he/she is done, then the one-to-one arrangement has concretely demonstrated that there is the same number of pencils and rocks
The pairing-off of the members of one set with the members of another set such that each member of the first has exactly one counterpart in the second and each member of the second has exactly one counterpart in the first The method of pairing off need not be effective Notation: AB (set A can be put into one-to-one correspondence with set B) Operator See connective