I'm looking for references that show that left-handed or ambidextrous
children are known to be poorer at writing/printing at first (in the
early grades (K-1-2) than their right-handed peers. I know that read
this somewhere but cannot not find any sources. Please find it for me.
I need this information quickly (by tonight for a meeting with my
son's teacher in the morning -- if you can get me the references by
tonight I would be happy to provide a tip.) Thank you.

This may be too late, but it might be helpful.

The Handedness Research Institute
Indiana University
http://handedness.org/action/leftwrite.html

Googlenut