This was a big issues for DS when he was in 4th grade, and I did some afterschooling with him in a focused way for the first time. At first he became really upset when he saw math problems on ALEXS.com that he couldn't do. Tamtrum city. School was too easy, and things on Alexs were too hard.
I believe that when a child is kept very far below their readiness level in their school learning, that the zone of activities in the 'readiness level' shrinks - and temporarily dissapears - The Goldilocks Problem!
Yes, my son recovered (to some degree - who knows how much overall potential is still 'in there' which might someday be reclaimed?) to the point were he can show interest in material that is 'rather easy' and 'rather difficult' as well as 'just right.' I listened to him tantrum day after day while he tried to do the Math. I didn't lose my temper, and kept as calm as possible. I had to whisper to myself over and over: 'Better now than while he is away at college like it was for me.'
Once I saw what my son really could do, I was better able to advocate with the public school. There were attempts at enrichment, and support for subject acceleration, but at the last minute, the district send down the 'final no' in the form of personal verbal attacks on my DH and I. The next year we tried a private school, and within a month of knowing our son, they gave him the gradeskip. For my son, a very social kind of kid, he needed to be in classrooms where the expectaions where high enough that he had to sweat over the learning. Some kids are more internally driven, and can be accomidated just by leaving them alone, or with a mentor, of 1-1 parental attention.
We've never seen DS 'give up' in quite that way since.
Best Wishes,
Grinity