A conclusion is not a summary. Restating what you already said adds nothing, and it is what most coursework conclusions do — often by paraphrasing the introduction back at the reader.
A good one synthesises, showing what your points add up to, then answers the question a reader is entitled to ask: so what? Enter your topic and this tool lays out that structure.
Summary says what you covered: "This essay examined X, Y and Z." Synthesis says what they mean together: "Because X constrains Y, Z becomes difficult to sustain." Only the second tells the reader something new.
A quick test: could your conclusion have been written by someone who read only your topic sentences? If so it is summary. Synthesis requires the argument to have been made first, and it shows.
A reader who followed your argument is owed a reason it mattered — what follows for practice, for policy, or for how the subject should be understood. One or two sentences suffices, but their absence is felt.
Keep the claim proportionate to what you actually showed. An essay analysing one district does not license a recommendation for national policy, and overreaching at the end undoes credibility a careful argument earned.
New evidence and new arguments. Anything worth arguing belongs in the body where it can be supported; arriving in the conclusion it reads as something noticed too late to place properly.
Avoid apologising for the essay, contradicting your introduction, and closing on someone else's quotation. The final voice should be yours, making your own claim.
A sentence on what your argument does not settle reads as control rather than weakness. It shows you understand the boundary of your own claim, which is a mark of academic maturity and is explicitly credited in many rubrics.
Keep it specific and short. "This analysis covers urban settings only, and rural dynamics may differ" is useful; a paragraph of hedging suggests you do not believe your own argument.
Around 10% of the essay, usually a single paragraph and rarely longer than the introduction.
No. Anything worth arguing belongs in the body where you can support it.
You can, but it is rarely needed — the position already tells the reader. Opening with your restated thesis is stronger.
The opposite. A brief, specific acknowledgement of scope reads as control over your material.
Better not to. The last sentence should be your claim, not someone else's words.