Demonstrate your understanding of the theories and principles of child development, and play therapy. These may include, but are not limited to: biographical sketches of seminal people in the field, the history and development of a specific model of play therapy, evidence-based treatment interventions for a particular clinical problem or population, creation of a documentation system for the play therapy process, research of play therapy approaches to a specific behavioral or emotional disturbance, a comparison of the efficacy of two different theoretical orientations toward child treatment, etc.