Can anyone helps me to correct this?
She taught in our school from Aug.2017 to July.2018, she is responsible for 376 students from grade one to seven and taught subjects like Chinese and culture. She is good at using a lot of teaching methods to get students engage in the class. She can also tailor her teaching according to different aged students. For example, for grade one students, she likes to make the learning environment fun so she combined the knowledge with some songs. With those who are struggling with their study, she always works with them after class to keep them from falling behind. There are so many times that I found her still tutoring the students in the early evening. So at the end of the semester, I’m not surprised that 94％ of her students have successfully passed the test.

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Answer

You have introduced the subject of the sentence with a pronoun - she.
Start by telling us who 'she' is - Mrs Carols taught in out school from ...

First sentence needs to end with a full stop before the next starts, or use a connective instead.  Also the dates need to be written without full stops in them and with full month.

She taught in our school from August 2017 to July 2018. She was responsible...
OR
She taught in our school from August 2017 to July 2018 and she was responsible...

As you improve you can make your sentences less repetitive.  Most start with She at the moment, another common start is I for the start of sentences.
Just using another word like 'her' or her name would help, or change your sentence around to start with other words - you managed this in the sentence: With those who are struggling with their study, she always works with them after class to keep them from falling behind. - This shows you are already improving and creating more complex sentences.

The entire work is easy to understand and gives lots of positive information. Well done.

Answer

Is 'She' still teaching at the school? The tenses are very confusing.