The odd girl out

There is one student in my English class who is from a lower form. You see, my class prepares students to sit for the 1119 English but this girl is only in Form 2. What business has she in my class?

You see, her father found that Form 2 English class is too easy for her daughter and hence requested to be emplaced in a higher form. She is indeed comfortable with the other older students as her standard of English is comparable to theirs if not better. I have marked several of her essays and they prove that she is not a misfit. Her essays are a joy to read as they are very interesting and written in good English and I hardly need to put my red pen to good use. All I look for are the vocabulary and interesting expressions which I tick as weightage for the final marks to be awarded.