Montessori believes each child is an individual. So each child will learn at his or her own pace. The teacher's job is to observe and guide the child on according to his/her interests/needs.
This is just a short explanation. I can go on n on for hours about it! lol
There are Montessori equipments designed to help children to learn, divided into areas 'Language, Maths, Practical life, Sensorial, Cultural'. Each area has its own materials and exercises to allow children to learn and explore. There's no homework as such, at least for nursery age children. I'm not trained for teaching primary aged children in a Montessori environment so I do not know. Why do they need homework at this age anyway?
As I've said, each child is an individual and therefore we look at the child's progress, and NOT on how he/she performs compared to others.