I lost five scores in learning on internet

Almost teachers in our school took part in learning on internet, which is the connection between technology and teaching. There are 6 models that will be finished by trainees. I think I am very careful for my learning. Before I do the homework on internet, I always check the requirements several times. After I finish it, I'd like to check it attentively. But when I check the final scores before the deadline, I am surprised to see I lost 5 scores out of 40 in model 2. I am so sad. I lost 0.03 scores in Model 1. Now I lost another 5 scores in Model 2. Why do I make some simple mistakes? I think I should do my job at one time. I can't do two things at one time. Maybe this is one important point I learned from Model 2. I hope I can do better in Model 3.