Would it be worth a shot to fill out an app with a portfolio or not?
Totally worth a shot!
I am wondering if it is worth it for her to remain in third grade, or if we should discuss a grade skip with the school.
I think it's wise to discuss it with the school and get their perspective. You can always decide to stay as you are, or make plans for next year.
I think that since she is being accomidated, that you can allow things like 'social fit' to play a role. Does she have intellectual peers where she is now? Is the current 4th grade class have a nice reputation for friendliness? Are there other kids going with her to her 4th grade classes? Does she get to do her 4th grade classes inside the 4th grade TAG program?
Since she is new at school, it might be nice to go to 4th grade full time so she can consentrate her social efforts on the group that she seems destined to join, one way or the other. I'd present it to the school that way.
Smiles,
Grinity