Wil Oonk

Als ik aan Jan zijn visie op wiskundeonderwijs denk, schiet me als eerste te binnen hoe hij op nationaal- en internationaal niveau, grote groepen collega’s op een ogenschijnlijk simpele manier wist te enthousiasmeren voor betekenisvol onderwijs. Dat deed hij bijvoorbeeld door met mooie contexten en doordachte materialen te laten zien hoe je leerlingen van jongs af aan kunt leren genieten van wiskunde!

Maarten Dolk

Een optimist pur sang. Hij zag overal kansen en kon plannen in succes omzetten.

Sol Garfunkel

For those of you who didn’t have the privilege of knowing and working with Jan de Lange, you missed a force of nature. Jan was a man of
extraordinary energy. He commanded any room he walked into. As director of the Freudenthal Institute in Utrecht in the Netherlands, he made
an outsized impact on mathematics education—in the Netherlands and throughout the world.
Sol Garfunkel, mathematician, USA

Michiel Doorman

In aanvulling op de hierboven al genoemde video uit 2016 (ICME): This afternoon was devoted to key aspects of the Dutch didactic traditions. Jan left an important mark on how the didactics of mathematics has developed in the last half century. He inspired many colleagues, nationally and internationally, with his enthusiasm for children’s curious minds, his mathematical eyes for the world around him, and how to make mathematics meaningful for all.

Vincent Jonker

Ik keek (rond 1998) naar hoe Jan een handgeschreven fax stuurde aan Tineke Netelenbos, toen staatsecretaris onderwijs, met een mate van ‘brutaliteit’ en ‘zwier’, in feit de opmaat voor het project RekenNet. Beide elementen – RekenWeb en Rekennetwerk – hebben zeer lang doorgewerkt in mijn eigen werk, en hebben ook weer de opmaat verzorgd voor het expertisepunt rekenen-wiskunde waar ik nu weer in zit, in zekere zin dus ook een ‘erfenis’ van Jan.

Mogens Niss

I vividly remember my first encounter with Jan, which took place at a conference in Hurdalsjøen in Norway in 1978, where we both made a presentation. I also remember our last pleasant and joyful meeting at a conference in Warsaw some years ago.
In the years between these two conferences our paths have happily crossed on numerous occasions, when we combined interesting and significant professional experiences and work with personal and enjoyable activities: At lots of conferences and other gatherings, including ICTMAs and ICMEs, at the inauguration of the Freudenthal Institute, at Istron meetings, and for several years as close collaborators in the PISA maths expert group.
During these more than four decades of professional collaboration and personal friendship there was never any doubt that Jan made a real difference in mathematics education, nationally and internationally. If I were to point out a single characteristic feature of all Jan’s contributions – apart from Realistic Mathematics Education, the Freudenthal Institute, including it’s branch in the USA, and PISA – it must be his never failing belief in students’ ability to independently think and reason mathematically beyond specific mathematical formalisms. For all his contributions Jan deserve immense praise and thanks.

Jan was born on August 26, 1943, in Leiden, the Netherlands, the son of Johannes de Lange and Johanna Maria Elisabeth Wakka. In 1996, he moved to Katwijk and was united in marriage to Els Feijs in 1996, the mother of his two children, Kasper (born in 1996) and Karlijn (born in 1998). Later, they divorced. He spent the last ten years of his life with Elsa Pronk, who lovingly took care of Jan during his illness.
Jan held a degree in Mathematics from Leiden University (1972) and earned his Ph.D. degree in Mathematics Education from Utrecht University (1987). His subjects were curriculum design and assessment.

After teaching mathematics at high schools for several years, in 1976 he was hired by Professor Freudenthal and Martin Kindt at IOWO (started in 1971), which in 1981 continued as OW&OC, a small institute part of the Faculty of Mathematics of Utrecht University. Later, he was appointed as a coordinator and in 1989 became full professor/director of the institute, in 1991 re-named as Freudenthal Institute (FI).
Under Jan’s leadership, the institute blossomed and grew, employing more than eighty coworkers at its highpoint in the early 21st century. Jan was a man with a mission: innovation in mathematics education by means of connecting research and practice (developmental research). He organized teams of talented people, in ways that let them shine. He was in favor of working in a flat, informal, maybe even somewhat chaotic, organizational structure. He connected all players, politicians, scientists, practitioners, textbook authors, using a variety of dissemination methods.

He was renowned for his powerful and relevant new ideas, being provocative and innovative with vision. He and his coworkers reached out internationally to validate theories. This resulted in many projects all over the United States, in Bolivia, South Africa, Indonesia, Malaysia, to name a few. You may best remember the Mathematic in Context middle school curriculum development project, in collaboration with Tom Romberg at the University of Wisconsin in Madison, USA, funded by the National Science Foundation. In 2003, the Freudenthal Institute USA was established. Jan and his coworkers participated in studies like TIMSS, NAEP and PISA, and in the Mathematical Sciences Education Board (MSEB) of the National Research Council, being Secretary of CIEAEM, organizing PME Conferences, and in boards of prestigious journals.

Nationally, Jan was unstoppable as well. He was involved in numerous projects and served as an advisor for many organizations. He was the instigator of several mathematics happenings such as the A-lympiad and the National Mathematics Days, which take place yearly until this day. As Jan observed his own children growing up, his research moved away from curriculum design to trying to understand our native mathematical abilities and interest. He came to see school as a place where that natural-born mathematical aptitude was systematically destroyed. In 2005, he founded the project TalentenKracht (Curious Minds), in which the curiosity of young children was seen as a starting point for scientific reasoning, and young children as the real researchers. Initially, six universities worked together to do research in this field. Jan was director of this project from 2005-2010.

In 2007, he retired from Utrecht University.
In Jan’s own words: “What I liked most about the Freudenthal Institute, where I spent most of my professional life, was the fact that, in reflection, every day seemed to be a fun-day.”

After his retirement, Jan relentlessly continued his work in the vein of the Curious Minds project by founding the Young Parents Academy, an academy for parents of young children (3-7). It’s aim was to make parents experience new and different ways of interacting with their curious young kids, look at their cognitive capabilities in a different way, and facilitate a more complete cognitive brain development, complementary to school. This took place in the context of Science & Technology (STEM). Serious play! Jan organized numerous successful sessions all over the country were parents and their young kids played together for two hours, eliciting many hidden talents, Jan with a loaded car with all sorts of toys that could elicit these talents. Many national and international inspiration presentations followed.
Jan was a renowned speaker. He was original, inspiring, provocative, and witty.

During his professional career, he presented at numerous conferences (ICME, PME, NCTM, AERA, CIAEM …) and for many organizations (some governmental) in more than 60 countries, becoming a most wanted invited lecturer with, eventually, all expenses being paid for, flying business class, and even earning fees. Others could not understand how any one person did as much as he did and could be in so many places, traveling all over the world with only a small athletic bag.
He also gave many general education inspirational and popular scientific presentations, with titles such as Dam Raid, Challenger XIII, Nautilus, STEM Education, Reasoning, Curiosity, Critical Reasoning, and The Sparkling Coefficient of young children. He more and more spoke close to his home, in local bars, restaurants, and the library. Jan organized “fun” popular scientific events such as paper plane contests.

In 2015, Jan did a TEDxAmsterdamED talk titled Curious Minds, Serious Play.
As for his publications, the list seems endless, including not only scientific articles, books, and chapters, but also popular scientific articles in journals and newspapers.
In 1994, Jan became Honorary Director of the Mathematics Education Research Institute at Central University Beijng, China, as a reward for the work done by the Freudenthal Institute. The title was awarded in Beijng as part of a two week series of invited lectures in China.

Jan was a sportsman, running (and biking), preferably on or near the beach almost in front of his house in Katwijk. He loved nature and traveling around the globe, accompanied by his wife and children, who caught the virus. Yearly conferences in the USA he lectured at were combined with vacation trips. In his later years, with great joy he started to discover Europe and his own country together with his partner.

Jan became committed to the local community of Katwijk with several initiatives.

Jan was an inspiration to all who were lucky to meet him, and generous whenever he could. He was a loving and caring father for his two children and partners.
Jan will be sorely missed.

chronologisch geordend

• Lange, J. d. (1981). Wiskunde A van start (PDF) Nieuwe Wiskrant. Tijdschrift voor Nederlands Wiskundeonderwijs, 1(1), 12-16.
• De Lange, J. (1987). Mathematics, Insight and Meaning (PDF), Proefschrift Utrecht. Promotor: Prof.Dr. F. van der Blij; co-promotor: Dr. A. Treffers (pp. 307). Utrecht, the Netherlands: Utrecht University, OW&OC. Zie ook een
  Boekbespreking van dit proefschrift en een info-pagina op ELWIeR.
• De Lange, J. (1993). Assessment in problem-oriented curricula. In N. L. Webb and A. F. Coxford (Eds.), Assessment in the mathematics classroom: National Council of Teachers of Mathematics (NCTM) 1993 Yearbook (pp. 197-209). Reston: National Council of Teachers of Mathematics (NCTM).
• De Lange, J. (1999). PISA Mathematics Framework. Paris: Organisation for Economic Co-operation and Development (OECD).
• De Lange, J. (2003). Mathematics for Literacy. In M. B.L. and L. A. Steen (Eds.), Quantitative Literacy. Why Numeracy Matters for Schools and Colleges (pp. 75-89). Princeton NJ: The National Council on Education and the Disciplines.
• De Lange Jzn, J. (2005). Wiskunde om gecijferd te worden. deel I (PDF) Nieuwe Wiskrant. Tijdschrift voor Nederlands Wiskundeonderwijs, 24(3), 42-48.
• Doorman, M., Drijvers, P., Dekker, T., van den Heuvel-Panhuizen, M., de Lange, J. and Wijers, M. (2007). Problem solving as a challenge for mathematics education in The Netherlands ZDM – International Journal on Mathematics Education, 39(5-6), 405–418 doi:10.1007/s11858-007-0043-2.
• De Lange, J., Feijs, E., Munk, F., Broekhof, K. and Cohen de Lara, H. (2013). Speel goed. Op ontdekking met je spelende kind (PDF). Den Haag: Sardes/Zwijsen.

• Section 13 Interview met Jan de Lange (door Michiel Doorman) uit het hoofdstuk over didactiek rekenen-wiskunde. Van den Heuvel-Panhuizen, M. (2019). Didactics of Mathematics in the Netherlands (PDF) European Traditions in Didactics of Mathematics doi:10.1007/978-3-030-05514-1_3.
• Catalogus Professorum UU: Jan de Lange