Good compost depends on a variety of ingredients to make the right mix.
To get healthy compost and avoid a slimy mess infested with fruit flies you need to add 'brown' materials (torn up cardboard boxes, wood shavings or straw work well) each time you add your 'greens' (such as fruit waste). The ratio needs to be about 50:50. It takes your compost about a year to rot down, after which you'll need to use it! Home-made compost is full of nutrients and perfect for beds or tubs around your school.