One aspect of self-esteem, or the lack thereof, works like this.
By the time a kid finishes the third grade, either he can read on grade level, or he can't.
If he can, he moves along with the most of the class. If he can't, he begins to fall behind.
From the fourth grade on, reliance on text books grows exponentially. If the books cannot be read, the student cannot learn. Concurrent with text books is greater reliance on written tests and examinations. The kid who cannot read is in trouble.
In many school districts, "social promotions" keep the kid moving along with his age group even though he is unable to do the class work. The kid understands that he is not the scholastic equal of his peers and becomes embarrassed. The only defense he sees is an offense which causes him to become a bully if he is big enough, or the class clown if he is not.
He tolerates school as best he can; living only for the arrival of his sixteenth birthday at which point he can drop out. He's thrilled. But the rush doesn't last long. He soon realizes that he is unfit for anything but jobs on the lowest rung of the ladder and hasn't much hope for improving his lot. Self-esteem? Less now than before.
How do we improve self-esteem among school kids? Recognize that reading is the backbone of education. In each of the first three grades, identify those who are in danger of slipping below grade level in reading. Immerse these kids in nothing but reading instruction until they are up to level. Monitor their reading progress until it is clear that they will not fall behind.
There are no self esteem problems on the first day of the first grade. If asked what they want to be when they grow up, how many would say, "I want to be a high school drop out and work for minimum wage."?
When they discover that they cannot read, self-esteem problems begin to arise.
Is there any way to validate this? I don't know. However, it is significant that the high school graduation rate across the US in 1998 averaged a mere 71%.
Three out of ten kids unable to make it through high school -- and this is after years of dumbing down the curricula.
Is there any reason to believe that things are improving even though, today, we are spending a national average of nearly ten thousand dollars, annually, for each kid in the public school system K-12.
There are plenty of interesting statistics to be found here:
http://www.manhattan-institute.org/html/cr_baeo.htm