The huge number of students in one class affects ...
I feel like this sentence is a bit awkward. Maybe change it to be something like this, " The larger the class, the less individualized attention for each student."
It goes without saying that educator ...
I think you should change the above part to this...
... that educators should have a creative method such as making groups when teaching in a big class. This would help to bring more attention to each and every student.
Also, I would delete this sentence....It is because each child has different need about attention thus teacher should ...
Overall, great job! I really liked your writing!