It turns out that much of what we throw away as garbage that eventually ends up in landfills can be recycled. This includes paper and cardboard, glass, and cans that can be recycled and yard clippings that can be com posted. When a person buys something at a store, a cashier usually puts it in a bag, paper or plastic. If we throw them in a landfill and waited 200 years, or even 2000 years from now, and dig them up, most plastic bags would still be there as plastic bags.
Paper sacks are reusable and recyclable, but they cost more than plastic.
Almost everyone goes to the store and buys something. Suppose you get each student in your school to do this for a year. Now suppose that this became a habit for the people in your school. Sort of like brushing your teeth. And everyone in your school did this for the next ten years.