Learning through play and free exploration are emphasized in the recent curriculum review in Hong Kong. This experimental project aims to investigate how children play with and without teachers’ direction instruction. Thirty-one children aged 4-5 (15 boys and 16 girls) attending a typical Hong Kong preschool participated in this study. The children are randomly divided into the control group and experimental group. The study consists of three phases: (1) Pre-test: Play without instructions for 30 minutes. A set of block play newly bought by the preschool is presented to children. Children are free to play and explore with the block as they like. (2) Treatment: Play with teachers’ instructions. In two-week period, the teachers will provide the experimental group with various instructions like picture book, puppet or probing whereas the control group will keep playing with the block set on their own. (3) Post-test: Play without instructions for 30-minutes for both groups. All block playing sessions will be videotaped. Behaviours of the children will be coded and analyzed based on the nature of play, content of play and complexity of ideas to delineate how teachers’ input may influence the quality of play and free exploration. Copyright © 2019 20th Pacific Early Childhood Education Research Association International Conference (PECERA).