For the past two decades, researchers and educators have been interested in integrating engineering into K-12 learning experiences. More recently, computational thinking (CT) has gained increased attention in K-12 engineering education. Computational thinking is broader than programming and coding. Some describe computational thinking as crucial to engineering problem solving and critical to engineering habits of mind like systems thinking. However, few studies have explored how computational thinking is exhibited by children, and CT competencies for children have not been consistently defined. Hence developing and implementing effective CT-related activities for children can be difficult. Therefore, exploring what computational thinking looks like for children is critical.Children can engage in, and learn to engage in computational thinking in both formal and informal settings. In this study, we are interested in exploring what computational thinking might look like in settings that approximate children's everyday experiences. More specifically, in order to investigate what computational thinking looks like when enacted by young children, we are interested in observing children and their family members engaging in open-ended engineering activities that are play-based. To accomplish this, we observed and video-recorded 5-8 year-old children and their families creating different structures together using large foam blocks that are out for free play at a science center. Based on our observations and analysis of the video-recordings, in this paper we report on the computational thinking practices and competencies children and families demonstrated while engaged in engineering play. Our findings can provide information needed to create a framework for promoting computational thinking in young children in informal settings.