Rheta DeVries is professor emerita of curriculum and instruction at the University of Northern Iowa. Betty Zan is associate professor and director of the Regent's Center for Early Developmental Education at the University of Northern Iowa. Their books include Developing Constructivist Early Childhood Curriculum: Practical Principles and Activities.

Rheta DeVries is professor emerita of curriculum and instruction at the University of Northern Iowa. Betty Zan is associate professor and director of the Regent's Center for Early Developmental Education at the University of Northern Iowa. Their books include Developing Constructivist Early Childhood Curriculum: Practical Principles and Activities.

Rheta DeVries is professor emerita of curriculum and instruction at the University of Northern Iowa. Betty Zan is associate professor and director of the Regent's Center for Early Developmental Education at the University of Northern Iowa. Their books include Developing Constructivist Early Childhood Curriculum: Practical Principles and Activities.