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Gerry Stahl

www.GerryStahl.net (internet)

Gerry@GerryStahl.net (email)

Professor Emeritus

College of Computing and Informatics

Drexel University

Philadelphia, PA, USA

Welcome to my website!

See NEWS below for announcements of my new books and eLibrary, which collects all my writings in 18 thematic volumes.

See RECENT below for announcements of my recent publications.


See PICTURES of our new home at Cape Cod. Now revised with photos of house after a year of living there.

We have a new granddaughter, Ruby Selah Stahl. She is already over one!


She joins another gem, granddaughter Nastasja Jade Stahl, who is already a teenager.


Group Cognition is now available at close-out prices: $10.75 (hardcover) or $10.21 (Kindle) from Amazon!

eLibrary of my Aggregated Texts.
All eighteen volumes now available -- most for free in PDF, iPad and Kindle formats; also in inexpensive paperbacks. These volumes bring together and organize all of my writings and presentations.

PDF versions of all volumes updated for 2017! Quick download of all pdf volumes of my Aggregated Texts from the eLibrary


Available from Cambridge University Press in hardbound and Kindle versions:
Constructing Dynamic Triangles Together: The Development of Mathematical Group Cognition
A longitudinal analysis of how a team of young girls adopted group practices of collaboration and mathematical problem-solving. The fine-grained interaction analysis of how the group interacts by negotiating and then following dozens of group practices--in collaboration, math discourse, software usage, dynamic-geometry construction and the comprehension of logical dependencies--provides a model of CSCL design-based research and the study of group-cognitive development.

New book -- self-published collection of essays:
Essays in Philosophy of Group Cognition
The philosophy of group cognition, a post-cognitive paradigm of CSCL research. Essays explore the concepts and implications of intersubjectivity, joint attention, common ground, shared understanding, etc. Compilation of 8 essays available as inexpensive paperback or free pdf, epub, mobi.

New book -- self-published collection of essays:
Essays in Group-Cognitive Science
The science of group cognition -- how to analyze computer-supported collaborative learning. Discussions and examples of methodologies including interaction analysis and group-level coding used in the VMT Project. Compilation of 9 essays available as inexpensive paperback or free pdf, epub, mobi.

New book -- self-published collection of essays:
Essays in Collaborative Dynamic Geometry
This volume includes analyses of student teams using the VMT environment with multi-user GeoGebra. These studies are related to the presentations in in Translating Euclid and Constructing Dynamic Triangles Together. They extend those discussions with in-depth case studies. A compilation of 10 essays available as inexpensive paperback or free pdf, epub, mobi.

New book -- self-published collection of essays:
Essays in Online Mathematics Interaction
These are case studies of student teams using VMT to work on problems in the mathematical domain of combinatorics. The early versions of VMT used here included a generic whiteboard for sketching graphical representations. Data from these sessions was analyzed by a number of researchers in addition to the VMT project members.The essays in this volume were co-authored with close colleagues. This compilation of 7 essays is available as an inexpensive paperback or free pdf, epub, mobi.

Translating Euclid is available in paperback and e-book.

Studying Virtual Math Teams is available in paperback and e-book.

Group Cognition is available at very low cost.

Webinar on Group Cognition is now available as a brief interview (5 minutes), a summary presentation (10 minutes) and a full webinar (90 minutes).

YouTube videos of my keynotes, talks, a seminar, an interview.

Pictures, slide show and YouTube video of my retirement events, including College retirement party and CSCL 2015 Conference social event honoring my retirement in Gothenburg, Sweden.

External Websites

my eLibrary -- CSCL-Community Blog -- my Amazon -- my Google -- my Scholar -- my YouTube channel -- my Lulu book store -- my Smashwords free ebooks -- ijCSCL website -- ijCSCL at Springer -- VMT Lobby -- VMT Wiki -- mathforum VMT wiki -- mathforum.org -- ISLS -- post -- my webpage at CCI Drexel

My Research Specialty

I am a researcher and professor emeritus of information science. My current research (from 2003 to the present) focuses on the Virtual Math Teams (VMT) project at Drexel University's College of Computing and Informatics, the Math Forum and Rutgers-Newark. This project is extensively documented in my book on Studying Virtual Math Teams. Our research team uses chat interaction analysis to explore what takes place in online discussion of math by students. The background and motivation for this research in my previous research from 1990 to 2005 is presented in my book on Group Cognition. My recent (2013) book, Translating Euclid, discusses the redesign of geometry education in terms of: cognitive history, contemporary philosophy, school mathematics, software technology, collaborative learning, design-based research, CSCL theory, developmental pedagogy and scaffolded practice. It is a multi-dimensional reflection on the VMT Project, including the very latest ideas and findings. My new book (2015), Constructing Dynamic Triangles Together, analyzes how a team of three junior-high-school girls developed their mathematical group cognition through eight hour-long online sessions using VMT to learn dynamic geometry.

My specialty is Computer-Supported Collaborative Learning (CSCL). I am the founding Executive Editor of the International Journal of CSCL (ijCSCL). I have presented at every international CSCL conference (1995, 1997, 1999, 2001, 2002, 2003, 2005, 2007, 2009, 2011, 2013, 2015) and have collected many resources about CSCL on my website.

All of my own publications are available on this site, listed chronologically. My eLibrary collects most of these writings in convenient volumes. My CV details my academic career. My grants and research during the past 20 years are documented on this site. At Colorado and Drexel I have taught courses on CSCL and Human-Computer Interaction (HCI)--how to design software to support collaborative learning, knowledge building and group cognition by online groups. My website also includes glimpses into my biography and personal life.

VMT Research Project VMT

Virtual Math Teams (VMT) is a research project that I have directed since its inception in 2003 at the iSchool and the Math Forum at Drexel University in Philadelphia. A group of PhD students, Math Forum staff, interdisciplinary faculty and visiting researchers collaborate on the project. We are developing an online service for math students to meet in small groups online to discuss challenging mathematical topics. We study the usage of the technological environment that we designed for this service, using a method of chat interaction analysis that we have refined. The project is guided by theories of collaborative learning, community knowledge building and group cognition, that we are exploring.

If you register and log into the VMT Lobby, you can enter the VMT Sandbox room to explore the functionality available there. You can also join a chat room or even create one to invite people to for collaborative online chats. There is an introduction to VMT for students, parents, teachers and researchers at the Math Forum VMT web page. A list of publications about the VMT project is available. The most important analyses of the VMT Project are collected in Studying Virtual Math Teams, which includes 28 chapters by members of the VMT research team, visiting researchers and international colleagues.

Recent Publications

My recent publications delve into philosophic aspects of group cognition as the foundation of CSCL:

Stahl, G., Koschmann, T., & Suthers, D. (2014). Computer-supported collaborative learning: An historical perspective. In R. K. Sawyer (Ed.), Cambridge handbook of the learning sciences, revised version. (ch. 24, pp. 479-500). Cambridge, UK: Cambridge University Press. Web: http://GerryStahl.net/pub/chls2.pdf.

Stahl, G. (2014). The constitution of group cognition. In L. Shapiro (Ed.), Handbook of embodied cognition. (ch. 32, pp. 335-346). New York, NY: Routledge. Web: http://GerryStahl.net/pub/embodied.pdf.

Stahl, G. (2015). Computer-supported academically productive discourse. In L. Resnick, C. Asterhan & S. Clarke (Eds.), Socializing intelligence through academic talk and dialogue. (pp. 213-224): AERA Publications. Web: http://GerryStahl.net/pub/lrdc2015.pdf.

Stahl, G. (2015). Conceptualizing intersubjective groups. International Journal of Computer-Supported Collaborative Learning. 10(3) Web: http://ijcscl.org/?go=contents.

Stahl, G. (2016). The group as paradigmatic unit of analysis: The contested relationship of CSCL to the learning sciences. In M. A. Evans, M. J. Packer & R. K. Sawyer (Eds.), Reflections on the learning sciences. (ch. 5). New York, NY: Cambridge University Press. Web: http://GerryStahl.net/pub/ls.pdf.

Stahl, G. (2016). From intersubjectivity to group cognition. Computer Supported Cooperative Work. Web: http://GerryStahl.net/pub/intersubjectivity.pdf

Constructing Dynamic Triangles Together book Analysis cover

I published Constructing dynamic triangles together: The development of mathematical group cognition in November 2015 -- the result of my first year of "retirement." It follows the interaction of three female students through their whole collaborative experience of exploring dynamic geometry during eight hour-long online sessions in the VMT environment.

The recent availability of dynamic-geometry software provides an exciting opportunity for innovative approaches to math education. This book reports on an extensive research effort, documenting the cognitive development of a team learning in that online social setting. The extended case study shows how the team enacted the tools and adopted group practices within an educational research project, which was designed to extend and support their ability to collaborate, to engage in mathematical discourse and to explore or construct dynamic-geometric figures. As a whole, the book provides detailed empirical support for the theory and practice of group cognition. The book documents the findings of the VMT Project as a paradigmatic example of CSCL exploration.

Stahl, G. (2015). Constructing dynamic triangles together: The development of mathematical group cognition. Cambridge University Press. Learning in doing: Social, cognitive and computational perspectives series. Web: http://GerryStahl.net/elibrary/analysis. Web: http://www.cambridge.org/la/academic/subjects/psychology/educational-psychology/constructing-dynamic-triangles-together-development-mathematical-group-cognition?format=HB

Translating Euclid book Euclid cover

I published Translating Euclid in 2013. It proposes a way of reinvigorating the study of geometry and brings the reports on the VMT Project up to date.

How should one translate the classic-education approach of Euclid's geometry into the contemporary vernacular of social networking, computer visualization and discourse-centered pedagogy? The birth of geometry in ancient Greece and its systematization by Euclid played an important role in the development of deductive reasoning and science. As it was translated and refined over the centuries, however, geometry lost some of its cognitive power and its very nature became obscured. Recently, computer-supported versions of dynamic geometry have been developed, which afford visualization, manipulation, exploration, conjectures about constraints and construction of dependencies. Particularly within a context of computer-supported collaborative learning, a dynamic-geometry environment may be able to facilitate the experience of mathematical insight and understanding that was traditionally the hallmark of geometry.

Stahl, G. (2013). Translating Euclid: Designing a Human-Centered Mathematics. Morgan Claypool Publishers.

The 221 page book is published in the Morgan Claypool book series and is available from Morgan Claypool Publishers, Amazon and book stores.

Studying Virtual Math Teams book SVMT cover

I published Studying Virtual Math Teams in 2009. The book includes 28 chapters that discuss and analyze various aspects of the VMT Project. The chapters are written by the core VMT research team and by international collaborators and colleagues. The book introduces the theoretical, methodological, pedagogical and technological approach and findings of the project. Part I situates the research in the perspective of group cognition theory; Part II presents model analyses of interaction in the VMT environment; Part III analyzes aspects of the online discourse; Part IV reviews the design of the technology; Part V considers alternative representations and models of the interaction; and Part VI concludes with reflections on the theoretical implications of the research.

Stahl, G. (2009). Studying Virtual Math Teams. New York, NY: Springer Press.

The 600 page book is published in the Springer Press CSCL book series and is available from Springer, Amazon and book stores.

(Pre-publication drafts of chapters are also available for review online at http://gerrystahl.net/elibrary/svmt)

Group Cognition book book cover

I published Group Cognition: Computer Support for Building Collaborative Knowledge in 2006. The book includes 21 chapters that review and extend my research during the past decade. The chapters report on several projects to develop software systems (including AI support for group formation, summarization and interanimation of perspectives), on approaches to analyze computer-mediated small-group interactions and on theoretical reflections leading to the notion of group cognition as foundational for collaborative learning.

Stahl, G. (2006). Group cognition: Computer support for building collaborative knowledge. Cambridge, MA: MIT Press.

The 500 page book is published by MIT Press and is available for a reasonable price from the following sources:

Amazon.com: http://amazon.com/gp/product/0262195399,

Barnes & Noble: http://search.barnesandnoble.com/booksearch/isbnInquiry.asp?z=y&isbn=0262195399&itm=1,

MIT Press: http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=10926.

(Pre-publication drafts of chapters are also available for review online at http://gerrystahl.net/elibrary/gc)

The ijCSCL Journal cover

Recently ranked #2 educational journal in the world by ISI impact factor

The International Journal of Computer-Supported Collaborative Learning (ijCSCL) was founded in 2006 to provide a venue for publication of leading papers on CSCL research. I co-founded the journal with Friedrich Hesse, the director of the Knowlede Media Research Center in Tuebingen, Germany, and with a Board of Editors including about 40 leading CSCL and CSCW researchers from around the world. The journal is published quarterly by Springer, sponsored by the International Society of the Learning Sciences. Anyone who joins ISLS is entitled to receive paper and electronic copies of the journal. To join ISLS, go to ISLS.org. The ISLS membership fee is deducted from registration at the CSCL or ICLS conference. Most major universities subscribe to ijCSCL as part of Springer's package of educational journals. The full text of all papers in ijCSCL are available for free at ijCSCL.org. For instructions on submitting a paper to ijCSCL, go to ijCSCL.org. A book review and the introductions to previous issues are available on my ijCSCL page

CSCL Resources cscl logo

I have tried to gather some resources for people interested in Computer-Supported Collaborative Learning and for the community of CSCL researchers. I wrote some overviews of the field from my perspective:

Stahl, G. (2008). Chat on collaborative knowledge building. QWERTY, 3 (1). Retrieved from http://gerrystahl.net/pub/qwerty08.pdf.
...an informal discussion of my personal perspective on CSCL.

Stahl, G. (2008). Human-human interaction and group learning. Paper presented at the Human-Computer Interaction Consortium, Frasier, CO. Retrieved from http://gerrystahl.net/pub/hcic2008.pdf.
...a discussion of technology and pedagogy in the VMT project and in my HCI course.

Stahl, G., Koschmann, T., & Suthers, D. (2006). Computer-supported collaborative learning: An historical perspective. In R. K. Sawyer (Ed.), Cambridge handbook of the learning sciences. (pp. 409-426). Cambridge, UK: Cambridge University Press. in English, in simplified Chinese, in traditional Chinese, in Spanish, in Portuguese, in German, in Romanian, in Japanese.
...an overview of the history and issues of CSCL. It provides numerous references for further study and outlines a direction for future work. The view of CSCL, its origins and its future is very much a particular perspective -- that of the authors.

In addition to giving many presentations on CSCL in North America, I have given keynote talks (as well as other papers) in three other continents:

Stahl, G. (2009). How I view learning and thinking in CSCL groups. Opening keynote talk presented at the International Conference on Computers and Education (ICCE 2009), Hong Kong, China. Available at http://GerryStahl.net/pub/iccekeynote2009.pdf. Video: http://GerryStahl.net/cscl/videos/icce2009stahl.wmv Slides: http://GerryStahl.net/pub/icce2009.ppt.pdf

Stahl, G. (2005). Groups, group cognition & groupware. Opening keynote talk presented at the International Workshop on Groupware (CRIWG 2005), Racife, Brazil. Available at http://GerryStahl.net/pub/criwg2005ppt.pdf.

Stahl, G. (2003). The future of computer support for learning: An American/German DeLFIc vision. Opening keynote talk presented at the First Conference on e-Learning of the German Computer Science Society (DeLFI 2003), Munich, Germany. Proceedings pp. 13-16. Available at http://GerryStahl.net/publications/presentations/delfi Video: http://GerryStahl.net/cscl/videos/stahl.mov.

I post a CSCL-Community blog. I compiled a list of CSCL books on Amazon, I contributed to Wikipedia articles:

CSCL-Community blog: http://cscl-community.blogspot.com.
...news for people interested in CSCL, including announcements of new papers in ijCSCL.

Amazon listmania -- CSCL books: http://www.amazon.com/gp/richpub/listmania/fullview/R2OYK7US8LYVPN/.
...a bibliography of seminal books on CSCL, CSCL conference proceedings, Springer series of CSCL books, etc.

Wikipedia article on CSCL: http://en.wikipedia.org/wiki/Computer_Supported_Collaborative_Learning.
...a general description of the reserach field of Computer-Supported Collaborative Learning.

Wikipedia article on Group Cognition: http://en.wikipedia.org/wiki/Group_cognition.
...a general presentation of the concept of Group Cognition.

Additional resources related to CSCL -- including a number of videos -- are available from the CSCL page of this site.

My Publications books

My publications are available here on my website organized in a couple of ways. The most up-to-date and useful is the chronological listing. My older writings are categorized by genre; this collection includes informal essays, grant proposals and other materials that are not all included in the chronological list. My CV organizes my professional publications by type. I try to make all of my publications freely available on this site in full text, searchable by Google and Scholar. My ORC id is: 0000-0002-2844-9112.

I have collected my writings in a series of volumes, organized thematically and chronologically:

A monograph in MIT Press's Acting with Technology book series: Group Cognition:Computer Support for Building Collaborative Knowledge.

A collection of studies in Springer Press's CSCL book series: Studies in Virtual Math Teams.

My collected writings: Gerry Stahl's eLibrary.

My HCI Courses gerry

My courses are heavily computer-supported. A consequence of this is that the course materials and even the student work is freely available for everyone to share. My teaching at Colorado and Drexel is documented on my teaching page. Recent courses on designing Web 2.0 software to support collaborative learning, community knowledge building and group cognition are completely documented on their wiki sites:

Spring 2007, INFO 608: Designing Social Interaction Software.
...designing software to support the VMT user community.

Winter 2008, INFO 608: Designing IPL Social Interaction.
...designing software to support the Internet Public Library.

Spring 2008, INFO 110: Designing for CSCL.
...designing software to support the CSCL research community.

Spring 2008, INFO 310: Speech chat in VMT.
...designing speech chat software for the VMT environment.

Spring 2009, INFO 782: Issues in Informatics.
...a graduate seminar on post-cognitive theories of cognition.

Spring 2009, INFO 105: Introduction to Informatics.
...an undergraduate exploration of classic texts in informatics theory.

My Research History vmt eloc

Although most of my research during the past several years has been related to the VMT project, I worked on a variety of projects earlier. Since the development of the Web I have documented my research on my website:

Research at Drexel. grant proposals at Drexel and the Math Forum.

Research in Europe ITCOLE project, BSCL, Synergia.

Research in Colorado WebGuide, State the Essence, Organizational Memory, Articulate Learners, Gamble Gulch, L3D Lab, Communications Theory.

Research previously Hermes, OMOL, WebNet, CIE, TCA, CREW, OptoNet, consulting and programming.

My curriculum vitae (in HTML Web and PDF printing formats) contains exhaustive listings of my academic career and related activities, with links to the original source documents.

Biographical family

In the mid-1990's, when the Web was young, I started my website in much the same format as it has now. I experimented with including both professional and family materials on the same site. As you can see from the archived versions of my site from 1997, 2000, 2002, 2005, 2009, it has maintained that format for two decades now. The site still includes biographical data about my education and pictures of friends, family, home, recreation and leisure time activities, including a gallery of my sculpture.