Short tests are the HARDEST (excluding total mastery tests, which don't happen until college, and even then... I've only ever had a handful of ###-###-#### question tests, and most mastery tests don't start until gradschool and only in certain disciplines; medschool/ the Bar, etc.).
Think for a moment about what you studied. I'm assuming more than the answers to 10 questions? Maybe 20 or 30 or even 50? But he only got the chance to "show off" the answers for 10. And he had a little self doubt about 2 of them. He could have known all 20/30/40/50... except 2. In a 50 question test... that's an A at 96%!!! In a 5 question test... that's a D at 60%
With a 10 question test, that's a grade level PER question. A 5 Q test is even worse. 2 grades per answer!!!
He only missed 2 qs.
No one does their best all the time. Did you do your BEST in everything today? How about college? Highschool? Middleschool? Elementary?
Or did/ do you have headaches, off days, days you can't concentrate to save your life, days you're sad, days you should really be home sick, days where someone keeps kicking the back of your chair?
Not every test is going to be your best. Not every day is going to be your best.
And it's REALLY HARD to do your best at all when you feel like the teacher hates you (true or untrue, if it FEELS like they hate you, life gets very very hard). I've had crappy professors (I even helped get one fired... another story for another time). As an adult, I KNOW they have no authority over me. Kids don't know that, because it's not true. Teachers have parental authority (aka total) over them for most of the day. A bad teacher can RUIN school for years or for ever, or turn a previously happy hard working kid into a kid who hates themselves. And a teacher can be phenom, but a personality conflict is just as bad.
Kids stuck with a crappy teacher OR a great teacher but major personality conflict need a LOT of support and encouragement.