My apologies ann55, if our responses caused you to feel your question was silly! There is NO silly question. And really no one-size-fits-all answers. We can only give you general answers.

So much of a child's "fit" and success in a particular learning environment depends upon a wide variety of factors:
- the particular gifted child,
- the mix of kids in the classroom,
- the teacher,
- the school policies (including openness to advocacy),
- your State laws.

You asked about questions to discuss with schools. There are some in the post linked to the word "fit" in the list above. smile

If a time comes when your child needs more academic challenge and/or the company of intellectual peers, you may observe pervasive changes, such as those listed in this brief roundup:

- not so happy
for example: change in personality and/or outlook, feeling invalidated, unsupported, unaffirmed, left out, marginalized, ostracized, internalizing a sense of "guilt" for being "privileged" with higher-than-average intelligence, anxious, afraid to make a mistake, bored, hopeless

- withdrawn from friends
for example: saying classmates don't "get" her humor, aren't interested in the same things, she has to hide her intelligence and "dumb down" to fit in, etc

- change in reading habits
for example: lack of interest in reading in depth about topics of interest, and/or choosing genres influenced by popular taste of kids her chronological age and/or assigned grade level

- avoiding challenge
for example: shunning new experiences, procrastinating when faced with learning about topics which she may not be too interested in or naturally good at

- etc, etc (more at these related posts)

These observations may signal that a change is needed and may be overdue. These involve quality-of-life factors, rather than being quantitative.
For a quantitative measure, you might look for a trend in achievement test scores which indicate a lack of growth over time.