Existence

While talking with my kids today about George Washington being sworn in as our 1st President, one of my darlings had this gem:

7th grade student: Mr. H, I don't think George Washington existed.
Mr. H: Why?
7th grade student: Well, how do we know he lived. We don't have pictures or anything.
Mr. H: Well, we have signed documents, journals, and numerous paintings of him.
7th grade student: Well, I believe that Abraham Lincoln lived, but not George Washington.