"The first essential for the child's development is concentration. The child who concentrates is immensely happy."
- Maria Montessori
Maria Montessori observed that children under the age of 3 learned by absorbing their environment, experiencing it and being a part of it. There is no need to give an infant a formal lesson; only to prepare their environment to spark curiosity and include them in conversations, their surroundings and in the day to day activities of family life.
Even a Montessori nursery is set up for independence! Typically, floor beds are used in place of a crib so that when a child begins to move (roll, crawl, walk) they aren't restricted by the crib walls. This means the rest of a nursery is a "yes space". No rockers, no heavy furniture, no small, cute items only there to look at. Everything in the space is for the infant, used by the infant, and can be touched by the infant.
Infants love to move and their need and desire to move should not be restricted. So, it's typical not to use baby contraptions that prop up infants in a position they otherwise couldn't get into themselves or keep them somewhere they didn't choose to be. Bouncers, walkers, swings, bumbos, and even sitting up your child before they're ready to sit up themselves, are not recommended.
Infants are soaking up everything including language. It's important to speak to a baby as you would any person. Using a real voice (not a baby tone) and using real words (not shortened, cute phrases) is important because this is their chance to take it all in. Talk to babies about what you're doing, where you're going, who is around. Point out sounds, and colors, and smells. Acknowledge the sounds they make and respond to them. These are their first attempts at a conversation.
It's typical to have open shelves for infants; first to look at and eventually to reach. Less is more when it comes to their toys. Having a variety of items from different textures, colors, and sizes is a positive way to start. It's best not to have anything too distracting; either in color or noise.
Infants, like any human, cry when they are in distress. Sleep training or using the cry it out method is not used. It is understood that an infant needs you, and needs to know that you will respond to their cries, and support them in their time of need.