Hi Mireia! Rosie's suggestions are perfect, but there's one other thing you may want to change.

As you know, I'm a Primary Teacher, since the last year, but I'm not working in a school. 

Because you're writing for an audience of people who may or may not know what you do, it would be better to say: "As you may know, I've been a primary school teacher for a year." This means: some of you know this information, and some of you don't. 

But this is a VERY small point. :-)

The educational problems of Spain. Problems in Spain's education system/the Spanish education system would be more idiomatic.

Hello,

I want to explain some things about some problems in the education of mu country 'explain some things' is a bit colloquial. You could say 'I want to try to explain the problems with the education system in my country, Spain'. As you know, I'm a primary teacher, since the last year I've been a primary school teacher for a year, but I'm not working in a school yet/at the moment.

The biggest problem is that our politics politicians (no comma) don't believe in us. I mean that they invest very little money in our educational system, which means that we don't have enough teachers in the schools, we have a very low salary, with an excess of students by class with too many students in each class OR class sizes are too big, etc. But..this is not the only problem...these things...have very bad consequences: we can't assist to students as they need we can't give students the help they need. If we have 27 students in the class, we can't do individual work with them/we can't help them individually. And all of our students need help in some specific things.

But well, what can we do? We only can hard working can only work hard to try to do the best we can with our resources. And, of course, we have to fight with everybody to be recognized. Do you mean 'everybody has to join in the fight if this problem is to be recognised'?

The teachers are very important in all of societies, and it's the first step to be better. Do you mean 'improving teaching is the first step to improving a society'?

As say MALALA Yousafzai: As Malala Yousafzai says:

ONE CHILD, ONE TEACHER, ONE BOOK, AND ONE PEN CAN CHANGE THE WORLD.

I hope this helps!

The educational problems of Spain.

Hello,

I want to explain some things about some problems in the education of my country. As you know, I'm a Primary Teacher, since the last year, but I'm not working in a school.

The biggest problem is that our politics, don't believe in us. I mean that they invest very little money in our educational system, It cause, that we don't have enough teachers in the schools, we have a very low salary, with an excess of students by class, etc. But..it is not the only problem...this things...have very bad consequences: we can't assist to students as they need. If we have 27 students in the class, we can't do a specific work with them. And all of our students need help in some specific things.

But well, what can we do? We only can hard working to try to do the best we can with our resources. And, of course, we have to fight with everybody to be recognized.

The teachers are very important in all of societies, and it's the first step to be better.

As say MALALA Yousafzai:

ONE CHILD, ONE TEACHER, ONE BOOK, AND ONE PEN CAN CHANGE THE WORLD.