How do you structure your introduction in an exposition

[kazewolf]

I normally use the statement, then I will list all the arguments briefly as topic sentences.(I will extend on these arguments in my body of the paragraph.)

The task: Should schools ban their canteen from selling junk foods.
__________________________________________________ __________
Schools should ban their canteen from selling junk foods. Selling junk food is advocating obesity, which misleads the pupil from making the right food choice. Junk food is detrimental to one's health and can cause many lifestyle diseases.

My introduction is quite plain, hence why I am asking for your examples. If I made any mistakes, please do correct them.
Thank you.

EDIT: Sorry, wrong section. Please move this to "Editing & Writing Topics"
Thank you.