5. Model adaptation

When given new information, experts adapt their models to integrate it.

Novices either just add it onto their model, or they learn it as a new, independent situation (regardless of possible contradictions).

As per item 4., if students are not put in situations where they are forced to confront the contradictory models, the contradictions will most likely remain present and unaddressed.

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For example: 

The children who decided that $\frac27+\frac17$ has different answers in different contexts were simply adding the new information to their mental model without attempting to integrate it consistently with their existing knowledge.