How do we conceptualize and design mixed reality environments (MREs)? Here we describe a first pass at a conceptual framework and use it to inform the design of different kinds of activities for children to experiment with. Our aim was to investigate how different MRE setups affected children's exploratory behavior and their understanding of them. The familiar activity of color mixing was used: different setups were provided, where paint or light colors could be mixed, by using either physical tools, digital tools, or a combination of these. The findings of our study showed that novel mixes of physical and digital “transforms” engendered much exploration and reflection.