What Do You Look for if you think that your son has ADHD

I am having a tough go of it at school with my son as the teachers say that he is highly disruptive in the classroom. They think that I should get him tested for ADHD. My main issue with that is he can get involved in something here at the house (like video games or building something) and be conteb to do it for hours, which seems to contradict everything that the teachers are telling me. I don't want to not do something because it seems as though the school issues keeping getting worse.

Is there test or a doctor whom we could see to DEFINITELY determine what it is the matter, if anything? We are located in the Broward county area.

 My thesis adviser in graduate school is an "expert" in the area of ADHD. Here is a link to an article he wrote about some of the things you would look for if you suspect ADHD. Good luck!

http://www.eric.ed.gov/ERICWebPortal/custom/portlets/recordDetails/detailmini.jsp?_nfpb=true&_&ERICExtSearch_SearchValue_0=ED450292&ERICExtSearch_SearchType_0=no&accno=ED450292