The purpose of the study is to contribute with knowledge about how children aged 4-5 years build in preschool, what attracts the play and what they use their designs to. While also looking at whether it differs something between girls and boys construction play. For the study, participant observation was selected as the method and observations have been conducted in the mornings and afternoons, after the children taken breakfast and snacks. Participant observation was chosen as the method because I wanted to be able to question the children things while I observed in order to get as broad picture as possible out of the construction play, but also to get a picture from the children's perspective. The results show that childrens construction play is a big part of the everyday life in preeschool, and is characterized by many different factors, such as fine motor abilities, concentration and of course much play between children. Children are not aware of how important the game is for the construction of their own experiences and learning, but see it as a fun activity they love to engage in because they think it's fun and that they are good at what they do. Differences emerge between boys and girls play and is most clear when the girls and boys play together.