Some students think that grades do not reflect their real performance in class, whereas others believe that grades are a good indicator to show how they are doing in class.

I reckon grades are a good way to encourage students to study new things because they get satisfaction, may apply to a scholarship, and grades show capacity and skills that they already learned.

"I reckon" is a little colloquial, maybe out of place here.

First off, every student in the world gets satisfaction when they get outstanding scores ofn homework, tests, small quizzes, oral presentations, and so on.

"homework" is uncountable but the rest should all be plural.

If they are doing well in academic life and getting good grades, they probably feel excited about their performance.

Then, they will get a be especially interest toed in learning new things in class.

Consequently, students can improve their scores, for example, a B+ into a –An A-.

We say "a B plus" or "an A minus"

In this point, it is difficult to find cheap programs in the world, then many students try to get a scholarship in order to achieve their own goals.

I'm not sure what "in this point" is intended to express.

That is the reason becausethat many students try to get good scores to get a scholarship.

Don't say "that is the reason because" or "this is why because". "because" should, I think, mostly be on its own.

Therefore, they will learn more if they want to have a good grades.

I used to study too hard because I wanted to studydo my master’s abroad.

When we talk about doing degrees, we can say "I want to study maths", or English, or physics, whatever. A subject. But we never say "I want to study a degree in maths". We do, take, or complete degrees.

I'm not sure if you really want to say "study too hard" - that implies that bad things happened as a consequence. You overworked yourself, and got depressed, something like that. You wish you hadn't studied so hard.

This small habit encourages me to learn new things in my academic life.

Or maybe "encouraged".

Lastly, good grades supporthelp students to showing their capacitybilities and the skills that they've already learned.

"capabilities" seems to fit better.

Any student is proud of thknowledge acquired knowledge inin the classroom.

Maybe? Slightly strange sentence, not sure what to do with it.

All of this, thanks to getting better scores.

I remember when I was a student in high- school, I normally got excellent grades in math, physics, and chemistry; yet I had terrible scores in biology.

I can only remember ever seeing "high school" or "highschool", I don't think we ever hyphenate it.

After that, I started preparing for my biology class by myself, and finally got better scores, became more confident in that class, and I obtained more knowledge about the human system wthat was the topic in my classthe class was about.

To sum up, I agree that grades help to students to learn new things due to the satisfaction when they get good scores, to get a scholarship, and to show the skills already learned.