When school grades are notably lower than the feedback, scores, or grades from other experiences, it may be worth looking into the parity and objectivity of the grading practices themselves.

Assignments in the English Language Arts (ELA) may especially be prone to SUBJECTIVE evaluation, rather than OBJECTIVE grading practices.

Here is an old thread with a roundup of various grading practices which some have reported experiencing - http://giftedissues.davidsongifted....245083/Grading_practices.html#Post245083

That said, it is possible that your child may need or benefit from special accommodations and learning strategies to compensate for any potential weakness(es). Wrightslaw can be a good source of information on testing, IEP, 504, and more. https://www.wrightslaw.com/

Understood.org can also be a good source of information, and includes articles such as https://www.understood.org/articles/en/the-new-thinking-about-adhd-and-executive-functioning

Although you may already be aware of everything in this post, this post is not wasted if it may help someone else who reads it. smile