work out their own answers before reading the solutions provided here!). Conversely, if you want to focus just on the concepts, and are not interested in a detailed case study, then you can skip all of chapters 6 and 12 and the latter parts of chapters 7, 8, 9, and 11. If you are most interested in the implications that CWA has for systems design or research, then pay particular attention to chapter 12. If you are not interested in alternative approaches to work analysis, then you can skip chapters 3 and 4, although by doing so you will probably lose some of the rationale behind the approach described in the remainder of the book. Finally, from a graduate student's perspective, you can use this book, especially Parts II and III, to identify a topic for a master's thesis or doctoral dissertation. Although they are not always explicitly labeled as such, if you look closely you will find plenty of interesting and important research topics that have yet to be addressed.
Although I did not know it at the time, the sequence of events that led me to write this book began when I spent 1 year as a Visiting Scientist in the Section for Informatics and Cognitive Science of Risø National Laboratory during 1987-1988. It was during that time that I became a serious student of the ideas presented in this book. This immersion was followed by several extended stays at Risø, during which my understanding was reinforced, expanded, and deepened. I am forever grateful to Jens Rasmussen for making this invaluable learning opportunity possible, and to João, Lisbeth, Sandra, Tine, Jan, and Gunnar for introducing me to the Roskilde Festival and for turning my time in Denmark into an experience of a lifetime.
I would also like to thank the following people for very helpful and constructive comments or discussions concerning this book: Amy Bisantz, Suzanne Bødker, Sara Chen-Wing, Donald Cox, Cindy Dominguez, John Flach, Simon Goss, Saul Greenberg, Stephanie Guerlain, Karen Holtzblatt, Alex Kirlik, Tim Lethbridge, Gavan Lintern, Marshall McClintock, Chris Miller, Neville Moray, Bonnie Nardi, Annelise Mark Pejtersen, Suzanne Rochford, Penny Sanderson (who saved me from countless misunderstandings by suggesting the term formative), Janice Singer, Tom Stoffregen, Lucy Suchman, Fumiya Tanabe, David Woods, and Yan Xiao.
I am also indebted to the students who took the class on which this book is based. Without their probing questions and insights, this book would not be what it is. In addition, I owe an unpayable debt to all of my former and current colleagues in the Cognitive Engineering Laboratory at the University of Toronto. Their insightful contributions in exploring the ideas described in this book have taught me a great deal. Particular thanks go to the following for commenting on earlier drafts: Peter Benda, Cathy Burns, Sandra Chery, Renée Chow, Klaus Christoffersen, John Hajdukiewicz, Greg Jamieson, Elfreda Lau, Gerard Torenvliet, and Xinyao Yu.
There are a few people who deserve special mention. First, many thanks to Erling Johannsen and Annelise Mark Pejtersen of Risø National Laboratory, and John Hajdukiewicz of the University of Toronto, for either creating, or providing me with, many of the figures in the book. Second, special thanks to Marshall McClintock of Microsoft for providing very thorough feedback and for pointing me to relevant and valuable literature of which I was not aware. His pointers considerably broadened the scope of the book. Third, many thanks to Chris Miller of Honeywell Technology Center, who spent a 1-year sabbatical in our lab while this book was being written. His