You must also pay attention to punctuation indentation as well.  It is as almost important as spelling when you write.  Without these technical aspects, your writing will not look good at all and you will be perceived as uneducated (at least in English).  REMEMBER, always a space after commas, and 2 spaces after a full stop.  Okay?  You are a good and hardworking student.  So I always have great pleasure in correcting your writing. :)

More Attention In Spelling.

Nowadays fewer and fewer students pay less attention to English spelling.  It is a serious problem that is not good because no one can understand what you write.  At the same time your pronunciation will suffer as you cannot picture the words in your mind.  The other aspect is that students cannot pronounce when they encounter new words.

Why is this the case?  When students started learning English, they must learn how to spell but they did not pay attention and so after class, they forget how to spell.  The other reason is that teachers did not pay much attention to students spelling too.

I thought it was the responsibility of any teacher to make sure that students spell  words correctly.  Students need to work harder on their spelling.  Schools need to have some kind of spelling tests to evaluate on the progress of their students.

Due Attention Should Be Given to Spelling

Nowadays,fewer and fewer students pay less attention to spell in studying English. It's1 a serious problem that isn't good for studying English2.On one side,the pronunciation will more and more unclear.On aother side,students can't correct speak new words without spelling.

Why come with this appearance? The started of learning English is spelling, but students didn't work hard3. Consequently,they don't know how to spell after class.The other reason that the teachers don't pay more attention about students' spelling.

I thought that teacher make the best use of spelling when students start to learn English.In addition, students need to working-hard and practice more time. Schools can make some test about the spelling and get the information how about their learning.It will be a good measures for spelling well.4

1.  Try not to use this sort of contraction (short forms) for writing.  They are usually used for writing direct speech. as in he said, "It's raining today." 

2.  You must give a reason for what you have stated that it is not good for studying English.  Your next sentence is just a side reason, not the main one.  This is for good writing.  Nothing to do with grammar or spelling.  I want you to write well.  One way to do so is to write in your native language.  Then try to translate it.  At the same time, people like me who can unstand some Chinese can help you correct better.  I know it is more work but studying is not easy.  I know you work very hard and so I am sure you won't mind it at all.

3. I am sure the students work hard but they don't pay much attention as they didn't think spelling is important.  It's their loss.  I agree with you that it is partly the fault of the teacher.  If I was teaching them... There will be pop quizzes all the time in testing them spelling besides other things.

4. This would be 劃蛇添足