Teaching in Between
It is of course much too absolute to consider that a "child" ceases to be a child at the age of puberty and that all of the rules of adult teaching suddenly apply! It is therefore appropriate to consider briefly the sort of variables that apply in the teaching of what we might call "young adults," "teens," or high school age children whose ages range between 12 and 18 or so.
The "terrible teens" are an age of transition, confusion, self-consciousness, growing, and changing bodies and minds. What a challenge for the teacher! Teens are "in between" childhood and adulthood, and therefore a very special set of considerations applies to teaching them. Perhaps because of the enigma of teaching teen-agers, little is specifically said in the language teaching field about teaching at this level. Nevertheless, some thoughts are worth verbalizing, even if in the form of simple reminders:

(1) Intellectual capacity adds abstract operational thought around the age of 12. Therefore, some sophisticated intellectual processing is increasingly possible. Complex problems can be solved with logical thinking. This means that linguistic metalanguage can now, theoretically, have some impact. But the success of any intellectual endeavor will be a factor of the attention a learner places on the task; therefore, if a learner is attending to self, to appearance, to being accepted, to sexual thoughts, to a weekend party, or whatever, the intellectual task at hand may suffer.
(2) Attention spans are lengthening as a result of intellectual maturation, but once again, with many diversions present in a teenager's life, those potential attention spans can easily be shortened.
(3) Varieties of sensory input are still important, but again increasing capacities for abstraction lessen the essential nature of appealing to all five senses.
(4) Factors surrounding ego, self-image, and self-esteem are at their pinnacle. Teens are ultrasensitive to how others perceive their changing physical and emotional selves along with their mental capabilities. One of the most important concerns of the secondary school teacher is to keep self-esteem high by:
oavoiding embarrassment of students at all costs
oaffirming each person's talents and strengths
oallowing mistakes and other errors to be accepted
ode-emphasizing competition between classmates
oencouraging small group work where risks are more easily made
(5) Secondary school students are of course becoming increasingly adult-like in their ability to make those occasional diversions from the "here and now" nature of immediate communicative contexts to dwell on a grammar point or vocabulary item. But even in teaching adults, care must be given not to insult them with stilted language or to bore them with overanalysis.