The Portuguese word paradidático means that materials that weren't designed for teaching purpose may be used as if they were. For example, a comic book is not exactly to be used as teaching resource, however, teachers may use it to help kids to learn their first words or to get involved with reading. So, we use this kind of material as a didactic resource. 

Is there any term such as paradidático that means the same in English? 'Paradidactic' isn't in any dictionaries.