The climax

The final sentence of the conclusion is of course the final sentence of the entire text. Of all the sentences in the text, this is perhaps the one that deserves the most careful attention. This sentence we know as the climax, with the connotation that the text will end at its communicative high point. An alternative name, taken from the study of poetry, is the envoy (etymologically, the sentence that we send the reader away with).

As far as content is concerned, the climactic final sentence should not seek to say anything radically new. Its function is, ideally, to encapsulate in one pithy sentence the ideas elaborated in the final paragraph. What should in any case be avoided is a sentence which leans on preceding sentences for its interpretation. Such a sentence, exemplified by the italicized sentence in the following, will certainly sound anticlimactic and will severely weaken the effect of the text as a whole:

* ... Teachers must be given a much clearer understanding of where parents' responsibilities begin and where teachers' responsibilities end. And children must understand that better, too.

Much better of course is:

Teachers, and children too, must be given a much clearer understanding of where parents' responsibilities begin and where teachers' responsibilities end.

In constructing the last sentence of the concluding paragraph, it is often wise to experiment with a range of formulations. Principles concerning the construction of effective message units, apply with full force in this climactic sentence. Particular attention should be paid to the sentence-final position, which needs to be occupied by a forceful content word, preferably one that has positive, active connotations. Consider again the final sentence of the first example (And children must understand that better, too), criticized above for its dependence on the previous sentence. Formally, too, this sentence has the drawback of ending with a cohesion marker (too). Moreover, the words that immediately precede it, must understand that better, are unsuitable candidates for final position, being communicatively given, cf. the expression be given a much clearer understanding in the previous sentence. And what is more, the one word in focus, children, is situated towards the beginning of the sentence. Taken together, these reasons rule out And children must understand that better, too as a final sentence.
Let us now reconsider the second, rewritten example. This sentence displays a forceful structure, with syntactic parallelism underlining the contrasted and focused elements:

Parents' responsibilities begin
Teachers' responsibilities end

Yet it needs to be mentioned that the sentence would be further improved by a reversal that allows the text as a whole to conclude on a positive note (begin rather than end), with the clear implication in the envoy that parents are hereby recommended to take their responsibilities at least as seriously as professional teachers:

Teachers, and children too, must be given a much clearer understanding of where teachers' responsibilities end and where parents' responsibilities begin.