We like to call this whole process of developing the working thesis the "lather, rinse, repeat" process - you are constantly refining your working thesis to make it "cleaner" and more effective.
And someone should be able to theoretically argue against it (how successfully will depend, of course, on how persuasive you are) * it takes a side on a topic rather than simply announcing that the paper is about a topic (the title should have already told your reader your topic). " * it is sufficiently narrow and specific that your supporting points are necessary and sufficient, not arbitrary; paper length and number of supporting points are good guides here * it argues one main point and doesn't squeeze three different theses for three different papers into one sentence Most importantly, it passes the "So What? No one wants to write a paper that doesn't matter, much less read one. This means to construct a thesis statement about a problem that is still debated, controversial, up in the air. So, how might you reword this phrase to clarify this meaning to yourself and the reader? Otherwise, you might as well just argue that any old "place of your own" benefits self-confidence.
Don't tell a reader about something; tell them what about something. So arguing that treehouses can be dangerous-- while you could find a ton of evidence to support your view --would be pretty worthless nowadays. How can our thesis statement communicate to our readers that treehouses are significant places? It's a thesis that looks at what treehouses could be doing, and people would certainly be interested in following your development on this issue.
You are not simply reporting on a topic, such as "treehouses." While such a report might be informative for you or a handful of treehouse novices, it would not produce anything new in the repertoire of treehouse literature, and therefore would simply be repeating information that has already been established.
Instead, you are trying to find out something new relating to that topic (e.g., how does a treehouse contribute to the emotional development of a child?