Cardboard Hill

[love apollon]

Two blocks down from school
by the boarded up house on Catalina,
we rode banana boxes and garbage lids
down an icy face, grinning all the way.
 
(I personally find that those inconsequential details often add a sense of nostalgia, 
you've created a sense of nostalgia, someone looking back on their childhood.
I agree with changing smiling to grinning i think that was a positive change.)

One year we built a jump
that sent us flying uncontrollably
before landing in a pile of powder
at the bottom of the hill.

(The action here positively distracts the reader from that wistful sense of looking back and then 
you lead them into a slight tragedy, a secret among friends, that causes the reader to think about
how they as a young person might deal with a situation. I like this a lot.)
 
John broke his arm testing it out,
but we told his mom he'd slipped on ice
so she wouldn’t spoil the fun.

(looking out for the spirit of fun. I do agree that "testing it out" seems a bit redundant and almost slows the pace 
of this delicious bit of prose.)