| 1.) | Reasoning and proof requires continuing development. |
| 2.) | Therefore we extend the spiral curriculum to mathematical activities. |
| 3.) | With the competence based four level model (Disposition, Comprehension, Communication, Autonomy) for arguing the complexity of tasks that demand reasoning and proof can be identified. |
| 4.) | GeoGebra-Applets
support the continuing development of arguing, because they can visualize the arguments of a proof and
refer to one or more different levels of the previous four level model. |