I would remove the interrogation mark (usually called a "question mark," in my dialect) at the end of "Did you know that...?", leaving only the interrogation marks at the ends of the list items.
When I read a list like this, I imagine the ellipses (... marks) as drops of glue that will be used to stick pieces of a sentence together. The pieces
Did you know that...
- ...in Brazil an estimated one-quarter of children do not attend school?
stick to each other
Did you know that ... in Brazil an estimated one-quarter of children do not attend school?
and become a complete sentence.
Did you know that in Brazil an estimated one-quarter of children do not attend school?
If there were a question mark at the end of "Did you know that...", the pieces wouldn't fit together correctly. The pieces
Did you know that...?
- ...in Brazil an estimated one-quarter of children do not attend school?
would try to stick to each other
Did you know that... ? ...in Brazil an estimated one-quarter of children do not attend school?
but the interrogation mark would be in the way, floating strangely in the middle of the sentence.