Jealousy is very common in your life and specially in your school life because during that time people are just like modeling clay or liquid who can be shaped in any form. There could be many reasons for jealousy:
Jealousy in friendship:
Jealousy due to academics:
We all have that one friend in school who is unbelievably in academics , and we feel inferior to them and then ultimately there is the rise of jealousy. I feel some times this kind of jealousy is good until it reaches it's extreme. Because that could help you to reach a much higher level, but that happens only if you have your mind mostly under your control; which lets be honest is not the case when your in school.
Jealousy due to fame:
It is not necessary that you will be jealous to a celebrity kid in your school, it could basically be anyone. It could even be your best friend Because the whole school know them her/him but not you , she/he is always given preference over you and others.
Jealousy due to nature:
This kind of jealousy is the one which you really can not help because it is your nature to be jealous of anything and everything.
Jealousy due to other people:
This could occur when your friend is being given attention from that specific person of whom you have been trying to seek attention . The jealousy occurring could even crush your friendship and you would even start being mean to your friend.
Now, i would say all emotions are required in your life ,
so don't be disgust by jealousy because it is
But you should always try to control it right away or else ,
it is capable of creating a great mess.