With particular focus on the self-regulation of three to six year old children during the free-play period, this study is to examine the effectiveness of my teaching model, named the Verbal Plan and Evaluation(VPE) Program, which has been developed on the basis of Vygotsky`s genetic epistemology. The VPE program involves the three stages of i) the child`s freely choosing the verbal plan for play activities(Verbal Plan), ii) putting the plan into action (Action), iii) having the verbal evaluation of his/her activities performed during the free-play period(Verbal Evaluation). The verbal interactions with the teacher are emphasized in the first and third stages. For the empirical examination of its effectiveness, I collected data from a 36-weeklong case study of 24 children who were enrolled in five preschools(three kindergartens and two child-care centers) in Seoul. I employed the method of participant observation and an in-depth interview with teachers and the review of children`s documents as well. The results are summarized as follows. i) The VPE Program contributes to minimizing children`s impulsivity and improving their attentiveness to free-choice activities. ii) It has children feel more responsible for accomplishing their activities. iii) It helps children improve their verbal communication skills and expand their idea of play activities. My study has clearly demonstrated that one-to-one verbal interaction between teachers and children plays a great role in planning and evaluating children`s free-choice activities.