Correct my mistakes please!

Hello teachers~
I've written my essay and here it is.
Please correct my grammatical mistakes~
Thanks in advance!


I want to focus more on talking about children because I want to be a teacher in a public school, where most learners are children. I think the key-point in teaching children is making them interested in class. After achieving students' attention, teachers should focus on whether the attention would be lasted during the class. One of the ways to maximize childrens' attention introduced in the book is having various activities. Certainly, there are good points throughout the activities which help students participate in the class. However, I think these activities will distract students' attention. Whatever the activities are, the class tends to be divided into two groups. One is students who are actively participate in, and the other is students who are laid back and just watching what other students are doing. In the textbook which is used in my sociology of education class, it says that Korean teachers classify students into two groups as well. One group is full of students who is willing to enter a university and the other is not. If a teacher is not able to handle all students in the class, then she would decide to be with certain students whose scores are in the upper rank. I believe this is what our teachers have been thinking and I was also treated in that way in my school years. Unless we allocate far fewer students to a teacher, having activities in class might cause indifferent students left in the indifferent zone.