Grinity, you nailed it here... and not to mention that girls will learn to accept this the rest of their lives, causing all sorts of issues, especially mental/emotional ones! I am living proof of that, and I know several other moms around here have similar stories that can be traced back to being bored in grade school...
I shouldn't have implied that all boys will complain - a few boys will go the 'internalize' route. I know them. They are real, but so few.
I really really believed my teachers when they told me that being bored wasn't a problem, and that I should try harder to like my agemates, and pay attention in class. Sometimes I think that my brain's amazing abiltiy to change channels at the drop of a hat is 'induced ADHD' that I trained myself not to dwell on any one topic for any length of time because I was trying not to brood. It wasn't until my son went to school that I finally had words for 'what was wrong with me' and that I finally finally understood that it wasn't all my fault. Where were the swans when I needed them? Even in college, I just assumed that all my interesting friends were much smarter than I was. Sigh. I am so grateful that my son was able to show me the way. He has no confusion whatsoever about deserving to be taught even in elementary school.
Smiles,
Grinity