The test
Could an informed, reasonable person disagree with this sentence? If no, it is a description of your topic wearing a thesis costume. Social media has changed how teenagers communicate is not a thesis. Nobody disputes it.
From topic to claim
Three moves turn a topic into a thesis. Narrow the scope, take a position, and name the grounds.
Topic
Social media and teenagers.
Narrowed, still not arguable
Social media affects how teenagers form friendships.
A thesis
Because platform design rewards visible interaction over sustained attention, social media tends to widen adolescent social networks while weakening the reciprocity that friendships depend on.
The third version can be argued against, and it tells you what the paper has to prove: something about platform design, something about network breadth, and something about reciprocity. The outline is already in the sentence.
The because test
Take your claim and finish it with because, then name the two or three reasons the paper will defend. If you cannot finish that sentence, you do not yet have a thesis, and the problem is the research rather than the wording. This is the single most useful diagnostic I know for a stuck draft.
Common problems
- The announcement. This essay will discuss. Say the argument instead of promising it.
- The list. Three unrelated claims joined by commas. That is three papers.
- The uncontestable. True, important, and impossible to write eight pages about.
- The overreach. A claim your evidence cannot support. Hedge it to match what you can actually show.
- The fossil. The thesis you wrote before the research, still sitting in the introduction of a paper that argues something else.
Thesis statements change
Your first thesis is a hypothesis. You write to find out whether it holds, and often it does not, and the honest response is to rewrite the thesis rather than the evidence. Check the introduction against the conclusion before you submit. A surprising number of drafts argue two different things at opposite ends of the same paper.