This volume is based on results from an NSF-supported project aimed at clarifying the nature of principles that govern the effective use of merging new research designs in mathematics and science education. A primary goal is to describe several of the most important types of research designs that: have been pioneered recently by mathematics and science educators; have distinctive characteristics when they are used in projects that focus on mathematics and science education; have proven to be especially productive for investigating the kinds of complex, interacting and adapting systems that...