(for) was much better written IMO than Henry & Sarahs (against). The numbers for each could have been better researched but, as stated by WildBill, most people cannot interpret it correctly anyway. There is the possibility that the argument was weak because Henry & Sarahs hearts simply weren't in it. 
Considering that all three writers are high school students, pretty good job. They are young people still learning and honing their skills.
Back in prehistoric times we had something called DEKA. A debate club where you had to argue either side depending on which you were assigned. A really fun learning experience that taught you to see opposing views and opened your field of vision. Probably something akin to a lawyer.