Advice about Dog training

[Klynne]

I have a 10 month old pomeranian. When I took her to the basic obedience class, at 8 weeks old, she was very good. Now, that I am in the advanced class with her, she loses it, can't focus on the tasks and, barks at the other dogs. I take her on walks every day. When she was younger, she ignored cars driving by, but now, she just goes crazy. Not every time. Sometimes, the cars will go by and she ignores them. Some days she just loses it. What we have been doing on our walks, when I see a car is going to pass, is tell her to sit, or lay down, and look at me. I will give her a treat. Sometimes it works, sometimes it doesn't. On the days she chooses to ignore the cars, once they pass, and she hasn't made a peep, I immediately give her a treat and tell her how good she is. I am thinking they way she reacts, is directly related to how I am reacting. Maybe, if I am relaxed, and not anticipating her reaction, is when she blows off any distraction. Any advice? Thanks, Kay