Testando maneiras para um bom feedback aos alunos

Olá pessoal, esse é o meu primeiro post no fórum e eu já comecei com uma dúvida:
Estou com uma turma de inglês composta por adolescentes que já têm uma certa noção da língua, e pensei em dar um feedback escrito (como uma carta) para os alunos, escolhendo algo em que tenham dificuldade. Meu primeiro feedback foi sobre uma das frases que eu pedi para que escrevessem em um exercício para casa, e eu ainda não enviei:

Frase: "I'm feeling so depressed and dumb today because I don't understand anything about Chemistry."

"Hello (nome), you did it very well! We just have to put some things right, ok? Let's do it together!

In your first sentence, did you notice that you were talking about feeling depressed and dumb because you didn't understand Chemistry in a specific time (today)? In this case, to sounds natural, we usualy use the present continuous, that express that you have been feeling like that before until the time you said that sentence and it continues. Example:

"I'm feeling so depressed and dumb today because I'm not understanding anything about Chemistry."

It means you can change this situation after the time you had said that (today), as you are having Chemistry classes. If you were talking about the fact that you don't understand Chemistry because you just can't learn it no matter how you try, you should use the verb "can" in the negative form, example:

"I'm feeling so depressed and dumb today because I can't understand anything about Chemistry."

The word that changes all the meaning is "today", because it's an adverb of time that tell us when an action happened, but also for how long, and how often. If you cutted off this adverb, the meaning would point to the fact that you are feeling depressed and dumb in your life just because you don't understand anything about Chemistry. Kinda exagerated, don't you think? You will get that!"

E aí, o que acham? Tem algo errado nesse feedback que eu não tenha percebido? Escrevi em inglês pelo incentivo ao contato com a língua mesmo, e porque sei que o aluno possui internet pra tirar dúvidas de algumas palavras e construções para entender e isso ajuda a aprender, mas também não estou tão segura ainda sobre minha capacidade de escrita.