Children's free play naturally enhances skills of observation, communication, experimentation, as well as development of rationale and construction skills. These domains, while synthesised, can lead to the development of certain process models regarding the way constructions could be designed, built and improved. The Design Process model constitutes a core concept of engineering. Blocks seem to be one of the best tools to use in order to work towards the development of such a model. This is a qualitative observational study in preschoolers' free playing with blocks. Eighteen children aged three- to five-years-old were observed and videotaped for four months to examine whether young children can demonstrate instances of precursors to engineering behaviour while building, by demonstrating similarities to the Design Process. Analysis of the video data showed that children demonstrated and articulated goal-oriented design, problem-solving thinking, innovation stemming out of synthesis of multiple designs, pattern repetition (PR) and design testing (DT).