Need help sexing chickens?!

[wyattm101215]

I bought seven Barred Rocks and 7 Black Copper Marans. I have an idea of what gender they all are but I would like some help. Here are some pictures....

Sorry that the pictures are bad.... I tried. Thank you!

 

[wyattm101215]

Forgot to say they are 6 weeks old!

 

[chente610]

4 cockerals and 3 pullets it seems to be on the barred rocks and 5 cockerals and 2 pullets on the black copper maran i am pretty sure but i may be wrong.