Shooting a group of teens

[Dankata]

I'd like to hear some opinions about recent shots I took of my friends' children. We went to this ranch and I wanted to practice some shots and different posing. I am just starting with my first DSLR, but I've been reading for almost two years and been using my Canon S5 IS daily, before I finally bought Canon T1i.
There were many things that did not allow me to achieve good quality photos. Using kit lens, built in flash, ran out of memory and couldn't shoot RAW.

I wasn't sure where to post this, maybe critique, but I saw posts about posing so this is what interests me in this case. What do you think about the poses, please I need ''harsh'' critique and not only about posing but light, angles, or anything else you can think of.

Thanks!

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[Dankata]

I think I made a mistake to post here, can I ask a moderator to move this to the Critique section?