how long should a thesis be?

how long should a thesis be?
i have summer homework. it’s for AP history, so it’s almost like a college level course.
for the thing, we have to make a thesis statement and an outline to back it up. how long should the thesis be?

A thesis statement should be one, single (can be lengthy) sentence long. It is your entire argument for the paper, summed up in one sentence. The rest is but background, elaboration, and evidence, ALL of which are aimed at that one statement. Think about the exact question the essay question or prompt is asking (post it if you want more help) and think of a one-sentence answer to that specific question. That is your thesis statement and the core idea of your essay. Every other sentence or point in the essay should support that central thesis statement/answer.