The PreTeXt-Runestone: Open Textbooks Engaging Undergraduates in STEM (PROTEUS) project is a collaborative project between the University of Michigan, the American Institute of Mathematics, and Runestone Academy. The project seeks to answer the following questions:

• How do groups of textbook users (students, teachers, authors, and researchers) work together to write interactive questions designed to elicit multiple ways of students’ thinking in classrooms?

• How do students and instructors use those interactive textbook questions in their classrooms?

PROTEUS is organized around four open undergraduate mathematics textbooks, Active Calculus, APEX Calculus, A First Course in Linear Algebra, and Understanding Linear Algebra, each of which supports a “STAR” team consisting of Students who have taken the appropriate course, Teachers with experience teaching the course, Authors, and Researchers. Each team is charged with developing content for their textbook following a design-based research process with rapid cycles of question development.

Each of the four textbooks is authored in PreTeXt, and this work is supported by development from Rob Beezer, the founder and lead developer of PreTeXt. The textbooks are housed on Runestone Academy, a Learning Analytics Platform developed and supported by Brad Miller. In addition, the project sustains the Open Textbook Initiative, led by David Austin, and a formative evaluation process, led by Katie D’Silva and Andrew Grillo-Hill of WestEd.