My little brother who is in junior high was asking me how truthful Marco polos stories were because in his social class a lot of the students were saying he was a liar since he never mentioned the Great Wall of china or how his autobiography was written by a fiction writer. He currently has a substitute teacher who has been giving very vague statements and not giving him any solid answers.
What I'm asking is how truthful these statements are and if there is sufficient evidence of his travels to prove that he did discover Asia?
Yes he did. The idea of Marco Polo having not reached Asia has been posited many times, and most notably (or most famously) written down by Frances Wood's Did Marco Polo Go to China?, an English 'historian' and 'sinologue'. This writeup by Igor de Rachewiltz goes into great detail about why this entire theory is wrong, and that Marco Polo really did get to Asia.