Zeile 81:
Zeile 81:
* [[EMS]] European Mathematical Society) Member of the Committee of Education of ESM (1988-1992);
* [[EMS]] European Mathematical Society) Member of the Committee of Education of ESM (1988-1992);
* [[GDM]] German Society for Mathematics Education) Scientific Advisory Board (1988-1994);
* [[GDM]] German Society for Mathematics Education) Scientific Advisory Board (1988-1994);
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{{gdmbeirat|1986|1989}}
* [[GTZ]] German Society for Technological Collaboration: Expert-Consultant and Evaluator of an Indonesian Mathematics and Science Project 1990
* [[GTZ]] German Society for Technological Collaboration: Expert-Consultant and Evaluator of an Indonesian Mathematics and Science Project 1990
* [[ICMI]] International Commission of Mathematics Instruction) regular Topic-Group and Discussion-Group organizer on congresses of ICMI, Member of IPC of ICME 11 in Mexico 2008
* [[ICMI]] International Commission of Mathematics Instruction) regular Topic-Group and Discussion-Group organizer on congresses of ICMI, Member of IPC of ICME 11 in Mexico 2008