[cowsaysoink]

I don't even know how you can justify the "only detrimental to poor kids."

It is far more an effect of the parents and household than it is economics of the house.

And that of the school hours is kind of wrong when you reach high school because that is when children take the bus or ride with friends with cars and drivers licenses.

Hours for school where I went (in the US):

    Elementary:    8:30am - 3:10pm
    Middle School: 8:20am - 3:00pm
    High School:   7:30am - 2:20pm

There is a huge difference in the high school, especially in bus in areas where buses come at anywhere from 6-6:45am. This isn't an issue caused by parent schedules or you would see similar times for middle and elementary school.

[akavi]

Wait, high schools starts earlier than Elementary?

I'm... dumbfounded by the idiocy of that (And a quick google indicates this isn't uncommon!).

Who on earth thought this was a good idea? Flip the ordering around and I'd bet you'd see significant improvement for practically no pain.

[shardling]

Typically it's because it's still dark out for the earlier block. Parents dislike having elementary school kids walk to school in the dark. (I have no idea whether it is actually less safe, but that's certainly the perception.)

[irishcoffee]

High school sports/after-school activities play into this timing