why?

I have just finished marking a few scripts from my good class. I mean, for their Trial PMR.
I am a bit frustrated thus it made me stop marking after a few scripts. I know that i did not put a high expectation in them. It was just that I HAD TAUGHT THEM HOW TO WRITE AN OPINION ESSAY just a few weeks before their trial. And i HAD TAUGHT THEM THEMES in The Prisoner of Zenda. And yet, why they still could not do it??
I mean, i didnt expect them to write excellent essays and get full marks. No. But i expect them to at least have the idea to write the essays and get above 15marks from 50 marks. They are in the best class in that school. and there are still a few who got less than 20marks.

AND THE BLAME IS ON THE TEACHER!!!

My mom told me, "they can't blame you. As you have already done your job in teaching the students. You have the proof that you have taught them to write the essays". Suddenly, my dad interrupted "Doa2 lah supaya Allah balas balik sape yg ckp mcm tu. Die tak nampak kita usaha ke dok". I was like "Errr, ok abah." haha.

I am now in the middle of doing a bit of analysis on what are their weaknesses, and mine too. huhu~

Ya Allah, kuatkan semangatku.