Leen Streefland's Legacy.

This Special Issue of Educational Studies in Mathematics honoring the life and work of Leen Streefland is based on Research Forum 5, Realistic Mathematics Education Research: Leen Streefland's Work Continues, at the 25th Annual Meeting of the International Group for the Psychology of Mathematics Education (PME), held in Utrecht, The Netherlands, July, 2001 (see PME-25 Proceedings, Vol. 1, pp. 221­253). The papers in this issue address the work of Leen Streefland at the Freudenthal Institute, and its continuation by his former colleagues and by international researchers who were influenced by his ideas. The essential problem addressed is how to develop a school mathematics curriculum that is grounded in the ex- periential reality of the learners (hence Realistic Mathematics Education ­ RME). In honoring Leen Streefland in this way, we are also honoring Hans Freudenthal, who was the first director of the Institute that after his death was named after him. Freundenthal was the originator of many of the ideas on which the continuing research is based, although (as elaborated in sev- eral of the papers) these ideas evolved and were modified and expanded in the subsequent and ongoing research. Some of these ideas include `math- ematizing', `mathematics as human activity', `anti-didactical inversion', `phenomenological didactical analyses', `guided reinvention', `long-term learning processes', `levels in learning processes', and `developmental re- search'. Freudenthal's work was an important source of inspiration for Stree- fland, as it also was for many others. In `The Legacy of Hans Freudenthal', a Special Issue of Educational Studies in Mathematics (Vol. 25, 1­2) that was published ten years ago, Streefland emphasized how Freudenthal cre- ated the context for further development. Paradoxically, he sometimes did this by putting people back on the track of their previously held ideas. For Streefland this happened for example with the issue of interweaving learning strands, which was an early part of his work. By higlighting the importance of this issue, Freudenthal revived it. Incidentally, this aspect of interweaving was by no means isolated within Streefland's work. Like no other at that time, he was focused on making connections, such as those between the different phases in long-running learning processes, between the current didactics of mathematics and the history of mathematics, between the different roles ­ student, teacher and researcher ­ which all who are involved in the learning-teaching process Educational Studies in Mathematics 54: 1­4, 2003. [ABSTRACT FROM AUTHOR]