As we know, it is very hard for students to find reasons and proofs by their own. We are sure that reasoning and proof requires [b]continuing development[/b]. One – very old – concept that deals with continuing development is the [b]“Spiral curriculum”[/b] by Jerome Bruner.

[size=150]*) revisiting a topic, theme or subject[br]*) complexity increases with each visit[br]*) new information are put in context with old information[/size]

[size=150]*) information is reinforced an solidified[br]*) progression from simplistic to complicated ideas[br]*) apply early knowledge for later course objectives [/size]

Usually the spiral curriculum was used for mathematical subjects and content areas. But it also possible to extend the spiral curriculum for typical mathematical activities and processes to enable a step-by-step acquirement of competence. Accounting this we generated a four level model to develop the competence “Reasoning and proof” from grade 5 to grade 12.