Discourse markers: making the logic visible

In a formal argument the reader should never have to guess how two sentences are related. A discourse marker at the start of the sentence says it openly: this is my next reason, this is a contrast, this is the same idea in other words, this is my conclusion.

• First and foremost, a school must be a safe place.
• The scheme is cheap to run. Furthermore, it requires no new legislation.
• In conclusion, the evidence favours gradual reform.

These markers are adverbials, not conjunctions. They begin a new sentence or follow a semicolon, and a comma comes after them; a comma alone cannot join the two statements.

Cleft sentences: What … is … / It is … that …

A cleft sentence divides one statement into two parts so that a single element receives the stress. A what-cleft keeps the focus for the end (What we need is time); an it-cleft puts it near the beginning and is ideal for correcting a wrong assumption: It is not X but Y that …

What + subject + verb + is / was + focus | It + is / was + focus + that + rest of the clause