It is impressive how many variables and individual differences there are among each individual (including children). Many times teachers follow a language book, which is the same to every student, not considering each pupil's characteristics, so it should not be a surprise when they begin to avoid/dislike the foreign language. Besides all these personal characteristics mentioned by the author, it is quite important to highlight the fact that people - specially children - are very vulnerable to situations and daily changes; adults may do an effort to study when they are sad or uncomfortable, but this is so much harder for the young ones.
Considering all these variables, each student must be seen as unique, endowed with a great repertory (acquired since in the mother's womb), so they should not be considered or taught ad a "tabula rasa", a empty vessel. Their opinions, ideas and knowledge of L1 and their hypothesis from L2 must be considered and valued, in a way that language becomes fluid and dynamic, focused on shared communication.

Guevara and Ordoñez mention in their study that "the imlementation of authentic performances led to considerable improvement of oral skills [...]. Communication, vocabulary and grammar were used in context and, so, with meaning and without actual specific lessons on them.".
It is very interesting that, in a playful and meaningful way, children developed a lot their oral skills, knowing how and when to use a varied of repertoire.
In Brazil we always hear that learning must be fun and significant for students, however, may times English classes for children are paper based (just activities in books), which makes it boring and not related to their reality.
Furthermore, in our country, there is a strong belief that no word in Portuguese must be spoken, ignoring the authors idea that "the effective, conscious use of the students' knowledge of their first language is a must in helping our monolingual children become good consecutive bilinguals". It is hard for children to like and learn English if they don't even know what they are doing and saying in the foreign language.