I ate my breakfast (eggs and a melangeyogurt bowl with sSkyr, oat flakesmeal and chocolate).

Mélange is a French word, the default would be "mix" in English. But what you are describing we could call a "yogurt bowl." Since Skyr is a brand name, it is capitalized

I tryam trying to gain muscle, so I have to eat a lot of protein, and I know theryogurt and eggs are both are great for that.

I am trying = you are actively / continuously trying
I try = from time to time / you make a habit of trying

Afterwards, I went to the school.

During the commute, I learned some words in English.

During the commute, I learned some words in English = during THIS commute TODAY
During the commute, I learn new words in English = during all of your commutes to school, as a habit

For example, today I learned the expression, "to have a blast," orand the verb "to board"."

Fun fact, "aboard" is easy to remember since it is the same as "à bord"

At school, first, I had class of Spanish class.

Classes will be referred to as "XXX class" and never "class of XXX," e.g., "biology class" as another example

The courseIt was pretty good.

You'd refer to the "course" as the entirety, as in, from day one until the last day. But each session counts as a "class"

I mhade some good intervenconversations, and as I learned my lessons, I was able to answer to some of the professor's questions during the class.

"Intervention" would not be used here. It's a word that tends to be used for serious contexts, typically where someone is stepping in (intervening) to prevent something bad from happening.

I don't know what you meant by it, but I am guessing it was about participating in discussions, so I wrote the edit for that.

"As I learned my lessons" doesn't work here, but you could say "during the class"

The second course was a course of English class.

My professor gave us backreturned the (different) tests we did last week.

"Different" is optional and I wouldn't include it

I was really surprised to get thea grade of 5 out of 20 ion the oral comprehension test because, basically, I always have great grades.

Nevertheless, I got the grades of 20 ina 20 on the written comprehension and written expression tests.

With the context above, we understand scores are from 0 to 20, so you can say "I got a 20"

It's reallly strange to have a 20 and a 5 in the same subject, but the professor is weird too, so I think ithat's the main reason.

After the English class, I had the sportPE class.

"PE" stands for Physical Education and is how we describe the general exercise program in schools (in America; I don't know for other anglophone countries). However, if your course is about a specific sport (which is more likely since, if I remember, you attend a university), you should refer to it by name instead. E.g., if this exercise course is specifically for running, we would call it "track and field" or "track" for short.

We had to run, and today was thee had a test.

"The" test implies we, the reader, know what test you are referring to. But you are just now mentioning/introducing it to us.

We had to predict our times for running a 500 -metters distance.

The length of the distance becomes an adjective here, and in this form, "meter" isn't pluralized

I'm not really good inat running, because I don't like it.

So, the bests did 1min30 seconds to finish the tour and I didThe fastest runner finished the track in 1 minute and 30 seconds, and I came in at 1 min 41ute and 41 seconds.

Rewrote a bit for clarity.

"Tour" can be heard sometimes in English for races, but it's definitely borrowed from French. The full length of your defined race could be referred to as the "track" here.

However, I was happy because I well predicted my times accurately, so I think themy grade will be pretty nicegood.

More natural

To finish the school day, I had a French test.

I'd recommend adding this descriptor since the post is about your day at school

We had to talk about a text published by Victor Hugo, a famous writter infrom the 1830's.

No apostrophe needed

It was about the death condamnationpenalty.

Formally being sentenced to death = receiving the "death penalty"

I'm not sure I succeif I passed it, but I did my betterst, and I think ithat's the most important.

"Success" is used as a noun and doesn't exist as a verb as you used it here.

Réussir un examen = to pass a test
Passer un examen = to take a test

Yes, "pass" is another faux ami

The French professor often gives bad grades so the. On our last test we did, I got 12,5 a 12.5, and it was the best grade ofin the class.

Decimal numbers use periods instead of commas

The class' average was about 9.

No need to make "class" into a possessive here

So, the bests did 1min30 seconds to finish the tour and I did 1min 41 / fastest runner finished in 1minute and 30 seconds, and I finished in 1minute and 41 seconds.

This is the only sentence that was not corrected, so it's the only one I'm correcting. "Tour" is definitely French and not used in English in the context of running a short, timed race or sprint. I'm not sure exactly what you ran, which is why I'm not suggesting an English word to replace "tour."

The French professor often gives bad grades so the last test we did, I got 12,5 and it was the best grade of the class.

I tryam trying to gain muscle so I have to eat a lot of protein and I know thery're both are great for that.

Afterwards, I went to the school.

"school", "work" and "university" are a little unusual in that you can "go to school" in general without specifying which school. It's generally more natural to say this as well.

During the commute, I learned some words in English.

For example, today I learned the expression "to have a blast" orand the verb "to board".

At first, I had class of Spanish class.

The courselass was pretty good.

I made some good interventions (?), and as I learned my lessons, I was able to answer to some professor's questions.

Not quite sure what you mean by "interventions" here.

The second courselass was a courselass of English.

"class" vs "course" is a little tricky, but "course" would be like your assigned study material for the semester/term, while "class" would be one period of learning it.

My professor gave us back the (different) tests we did last week.

I think you can omit different and it will sound more natural

I was really surprised to get the grade of 5 out of 20 in the oral comprehension test because basically, I always have great grades.

Nevertheless, I got thea grades of 20 in both written comprehension and written expression.

It's reallly strange to have 20 and 5 in the same subject, but the professor is weird too, so I think ithat's the main reason.

After the English class, I had the sport classPE.

"sport class" is more naturally referred to as PE (which is an abbreviation of physical education)

We had to predict our times for running 500 metters distance.

I'm not really good inat running because I don't like it.

So, the bests did 1 minute 30 seconds to finish the tour and I did 1 minute 41.

If you want a really concise way to write this, you can use "1m30s", but we usually don't abbreviate minute and then not abbreviate seconds also.

However, I was happy because I well predicted my times well so I think the grade will be pretty nice.

It was about the death condamnationpenalty.

I'm not sure I succepassed it but I did my bestter and I think ithat's the most important.

The French professor often give bad grades so in the last test we did, I got 12,.5 and it was the best grade of the class.

In English we use the "." (period/full stop/dot) as the decimal seperator.

The class' average was about 9.

"class" can also be an adjective, and is more naturally used here as an adjective than as a possessive noun.