P.W.
Hi M.
Yes, you definitely need to tell her about ADHD. Don't know what school system she is in, but it is difficult for them to do well in school. I have grandchildren with ADHD, they are on medication, however the one struggled in school until he was diagnois with ADHD. Then some of the teachers still gave him a hard time, because of his actions. Either go to the library or on the internet and get books on her level so she will understand what is going on in her life and why.
Good Luck
P.