- Designing GeoGebra Tasks for Visualization and Reasoning
- Duval's Model of Visualization and Reasoning in Geometry
- Operative Apprehension: From Quadrilateral Dissection to Dudeney's Puzzle
- Robust and Soft Constructions
- Soft Construction as Operative Apprehension to Foster Visualization and Reasoning
- Challenges
- Solutions of Challenges
- Answers of Challenges by Irina Boyadzhiev

# Designing GeoGebra Tasks for Visualization and Reasoning

- Author:
- Anthony OR 柯志明

Presentation in GeoGebra Global Gathering 2015
Or, A.C.M. (2013). Designing tasks to foster operation apprehension for visualization and reasoning in dynamic geometry environment. In C. Margolinas (Ed.)

*Task Design in Mathematics Education: Proceedings of ICMI Study 22*, pp. 89-98, Oxford, U.K. https://hal.archives-ouvertes.fr/hal-00834054v3.## Table of Contents

### Duval's Model of Visualization and Reasoning in Geometry

### Operative Apprehension: From Quadrilateral Dissection to Dudeney's Puzzle

### Robust and Soft Constructions

### Soft Construction as Operative Apprehension to Foster Visualization and Reasoning

### Challenges

### Solutions of Challenges

### Answers of Challenges by Irina Boyadzhiev