Highschool collaborative work in Physics/Chemistry

Teaching Physics and Chemistry in English with my French students (equivalent : 10th, 11th and 12th grade), I am interested in building a partnership with an American Highschool. It could be a common work on the internet with a collaborative website and video conferences or a real exchange program.
The field of study could be discussed and would deal with Physics, Chemistry and/or Environmental issues.
A small group of twenty students (maximum) could be easier to manage, but no real limits exist as soon as no physical exchange is organized at first.