Children’s play naturally employs skills of observation and experimentation that lead to the development of intuitive models for how things work.  These spontaneously occurring activities are precursors to engineering thinking that we recognize as preparation for future learning.  We are engaging in a research agenda to explore the learning progression of engineering thinking in young children’s development, to identify opportunities for expanding their thinking, and to foster interest in engineering.  Literature on early childhood development documents how students’ cognitive abilities develop over time.  However, little research has been done to document how these activities relate to activities that require engineering thinking.  In this presentation we will share some of our early results from a naturalistic study with preschool children’s constructions with blocks.  Our future goals are to learn how we can be more intentional about the activities, toys and devices we could develop that stimulate engineering thinking.