With the rapid development of advanced technology, some people believe that children can self-study without the assistance of institutions. Based on my experience and observations, however, I would take issue over such statement for two main reasons.

First and foremost, schools train students to be respectable citizens besides well-educated ones. Having to comply with school regulations, children gradually become more disciplined, which may result in their strict obeying to laws. Also, experienced teachers are certain to help the young to cultivate valuable moral lessons as well as survival skills that could hardly be obtained on their own. As educators definitely confronted failure at least once, the younger generations will be imparted know-how they acquired from such failing.

What is more, pupils have the opportunity to expose to practices. Since every school is supposed to be equipped with labs, learners can participate in experiments which can only be observed through screen without schools. For instance, after some certain tasks about plant cell, students will have a practice period to have real observation about it. Furthermore, extracurricular activities, such as competitions, trips to historical sites, are often held with the view to entertainment and studying. The effectiveness of learning process will, consequently, be boosted.

On the other sides, it is argued that there is an immense amount of information available on the Internet on a number of aspects of lifes. And it could be a better replacement for books and lessons at class. They forget, though, that a large part of such knowledge may be false, antiscientific, or even worse misleading on account that people can post anything without censorship. Whereas, schools are undoubted to provide trustworthy and vital insight.

In conclusion, I strongly believe that schools play an indispensible role in every successful students’ life. In addition to this, high-tech gadgets should be helpful assisting tools.

Please do not put the essay instructions in the "Subject" line.

Put it with your answer in the message body.

Subject: Please review my IELTS essay
Message Body:
Topic: Schools are no longer necessary because children can get so much information available through the Internet, and they can study just as well at home. (What is the complete topic? Does it ask for your opinion, or the pros and cons, or to what extent you agree? I cannot fully evaluate your essay without the instructions.)
My essay
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With the rapid development of advanced technology,

That is not exactly true. It is not the development of new technology that the topic refers to.

You need something like this:

With all the excellent educational resources on the internet, like Wikipedia, ebooks and online courses... 

These are sources that learners would use to educate themselves.

some people believe that children can self-study without the assistance of institutions. Based on my experience and observations, however, I would take issue over such a statement for two main reasons.

(Do not refer to your essay or your writing in the thesis statement. The reader knows and expects that you are going are going to give your reasons in the body paragraphs. That is the convention of an academic essay.)

First and foremost, schools train students to be respectable citizens besides well-educated ones. Having to comply with school regulations, children gradually become more disciplined, which may result in their strict obedience obeying to laws. Also, experienced teachers are certain to help the young to cultivate valuable moral lessons as well as survival skills that could hardly be obtained on their own. As educators definitely have confronted failure at least once, the younger generations will be imparted know-how (wrong words) they acquired from such failing.

What is more, pupils have the opportunity to expose (wrong form) to practices. (wrong word) Since every school is supposed to be equipped with labs, learners can participate in experiments which can only be observed through screen without schools. (wrong words)

I think you mean this: ..students will have lab classes where they look through microscopes or learn chemistry through experimentation.

For instance, after some certain tasks (wrong word) about plant cell, (??) students will have a practice period to have real observation about it.

For example, after reading about plants in a biology textbook, students will go to the lab to examine plant cells through a microscope. They can make their own drawings of different kinds of cells.

Furthermore, extracurricular activities, such as competitions, (missing word) trips to historical sites, are often held with the view to entertainment and studying. The effectiveness of (missing word) learning process will, consequently, be boosted. enhanced.

On the other sides, it is argued that there is an immense amount of information available on the Internet on a number of aspects of lifes. (The subject is academic education.) And it could be a better replacement for books and lessons at class. They forget, though, that a large part of such knowledge may be false, antiscientific, or even worse misleading on account that people can post anything without being checked. censorship. Whereas, schools are undoubted (wrong form and position) to provide trustworthy and vital insight. (incorrect word)

In conclusion, I strongly believe that schools play an indispensible role in every successful students’ (wrong form) life. In addition to this, high-tech gadgets should be helpful assisting tools.

(You never mentioned any high-tech gadgets in your essay. The concluding paragraph should not introduce new material. Besides, what do gadgets have to do with schools?)