I'm not sure presenting "simplified" tunes is the way to go with children. If you want to stick with notation, just get a basic book of session tunes. For the most part a notation of an Irish tune will only be a guideline anyway. I'd advise you to let her show you what she can do rather than telling her what her level is.

I'm reminded of the first lesson my daughter had in Irish step-dancing when she was only three and a half. The teacher made no preparatory remarks. She demonstrated a dancing step and asked my daughter to copy it.