My wife and I have been discussing homeschooling our two children (ages 9
and 12). Public school in the US seems to be completely concerned with
teaching kids how to do well on state standardized tests, and less about
learning.

I should say first that this is not about religion at all (most parents in
the US homeschool for religious reasons), my wife and I are atheists. Our
kids do OK in school as far as grades, but they are overwhelmingly bored and
I have to say I don't blame them. Public school just seems to be devoid of
any real content, kids nowadays are taught how to conform and do well on a
test they take every year from grade three onwards (usually eight years
old).

Now, I was a product of public schools, but I never had to take any
standardized tests until I was in high school (SATs), and while I do recall
being bored, I also remember having some excellent teachers who were able to
convey interest in a subject and effectively teach. Looking back as an
adult, they weren't hampered by any curriculum-by-decree, or the threat of
loss of federal funding if their kids did not "perform" on some pointless
test. That is not to say there were not problems that have always been
present with public schooling. John Gatto, a former school teacher, has a
good essay on the subject [0]. Here is a quote:

"Now for the good news. Once you understand the logic behind modern
schooling, its tricks and traps are fairly easy to avoid. School trains
children to be employees and consumers; teach your own to be leaders and
adventurers. School trains children to obey reflexively; teach your own to
think critically and independently. Well-schooled kids have a low threshold
for boredom; help your own to develop an inner life so that they'll never be
bored. Urge them to take on the serious material, the grown-up material, in
history, literature, philosophy, music, art, economics, theology - all the
stuff schoolteachers know well enough to avoid. Challenge your kids with
plenty of solitude so that they can learn to enjoy their own company, to
conduct inner dialogues. Well-schooled people are conditioned to dread being
alone, and they seek constant companionship through the TV, the computer,
the cell phone, and through shallow friendships quickly acquired and quickly
abandoned. Your children should have a more meaningful life, and they can."

[0] http://www.cantrip.org/againstschool.html