A letter to your father explaining the cause of your failure in examination.
Dear Father,
I hope you've received my Part-1 exam results. I didn't do well in Chemistry and failed by a few marks. Please don't be upset with me, it's not entirely my fault. Before the exam, I got really sick with malaria and had to stay in bed for a while. This made me very weak and I couldn't study properly. After I got better, I tried my best to catch up, but there wasn't much time, and I couldn't do well in all the subjects.
Adding to that, our Chemistry teacher got transferred, and the new teacher took some time to start teaching us. For more than two weeks, we didn't have a proper teacher, which made things even harder, especially for Chemistry.
I'm working really hard now to make up for it. I've improved in most of the subjects, and I'm confident I'll do better in the next exam. I hope you can understand and forgive me this time.
Please give my regards to Mother.
With affection,
X.Y.Z.