Differences and similarities between descriptive and prescriptive grammar

Hello there.

My name is Lina.

i'm not a native speaker but i'm interested in learning english. Now i'm taking a diploma course of ELT. I really need help in explaining those two things of english grammar. Can you please give me spesific example and evidence of each rules? If i were to teach english later on, which approach that you would suggest me to use and how do i go about it in my classroom. I would really appreciate it, if you can provide me (if you don't mind) a detailed lesson plan of the suggested approach.

Thank you so much and please do help me..