Writing prompt: Can We Bring Mobile Phone to School?

Student essay:
Hello! My name is Z, I am not opposition to students bring mobile phone to school. Because mobile phone is convenient that we can use it to make communication to our parents and friends, and it gives our great delight. There are also having some problems when we bring mobile phone to school, we disturb teachers and students while we use mobile phone, chating and writing message in mobile phone wastes time and money, mobile phone is serious harmful to our when we playing games and cheating in examinations. Here are my some opinions:
Fristly, if our bring mobile phone to school, we can't use it to play games or cheat in. Secondly, when we are in class, we shouldn't use it. Lastly, mobile phone is valuable and we must to gives it to ourselevs for safekeeping.

Corrected essay:
Hello! My name is Z. I am not opposed to students bringing mobile phones to school. Because mobile phones are so convenient that we can use them to communicate with our parents and friends, and they give us great delight. There are also some problems when we bring mobile phones to school. We disturb teachers and students while using mobile phones, chatting and writing messages on mobile phones waste time and money, and mobile phones are seriously harmful to us when we play games and cheat in examinations. Here are some of my opinions:
Firstly, if we bring mobile phones to school, we can't use them to play games or cheat. Secondly, when we are in class, we shouldn't use them. Lastly, mobile phones are valuable, and we must keep them safe ourselves.