Please look over this intro. paragraph and give me some suggestions! And maybe rate it out of 100? I'm a sophomore! (This is my first draft)...

That's a good start for a first draft.  The first sentence
is vague, however.  Try to avoid saying "thing" and the clause that follows the colon is
too informal and wordy.  You shouldn't put a "the" in front of Black Tuesday.  You also
have tense issues in that second sentence.  Were should be was.  Marks should be marked.
  The sentence that starts with "when people think" could be tightened up and
formalized.  In the sentence that starts with "starting," it should be half the banks
closed, you don't need "whole," and you should start the third point differently (so
it's not the same as the first point).  You shouldn't say "us" or "we" in a formal
essay.

So, in reading this intro paragraph, I assume that
you will be discussing the causes, consequences, and legacies of Black Tuesday.  Your
second to the last sentence is your thesis, right?  The last sentence sounds like a
transition, which isn't normally used in an intro paragraph.  It sounds like the topic
sentence of the first body paragraph.

If this were turned
in to me as a first draft, I would have given it 85/100.