What happens to a banana peel, a plastic bag, and a newspaper after you throw them away? Some materials break down in weeks. Others last for centuries. This project explores the difference. You build a compost column from plastic bottles and fill it with soil, fruit scraps, grass, newspaper, and plastic. Over two to four weeks you observe which items decompose (break down naturally) and which stay the same. You also sort everyday trash into four categories: reduce, reuse, recycle, and recover. By comparing your compost results to how real landfills work, you see why some waste creates problems like water contamination and methane gas.