Babies can participate in and watch a variety of arts and crafts activities. These should be as basic as possible, containing few steps and having a clear outcome at the end. For example, you could drop food coloring into some water, or, if a baby is old enough, have him drop some into the water. This will get him acquainted with colors by entertaining him. The mixing is fascinating for a baby to watch, and you can take the opportunity to talk to him about colors. You can also let him draw with large markers, crayons or pens, which will improve his motor skills.
The outdoors are a great place to carry out activities for babies, as they provide so much more stimuli than indoor environments do, from grass to trees to the wide variety of animals that live outside. You can take babies out for a stroll, provided there are enough teachers, and you can make these strolls more engaging by pointing things out, and asking babies to label things if they are starting to talk.
One of the key sets of skills that babies learn is movement: crawling, walking, gripping and manipulating objects in the world around them. There are a wide variety of ways to both teach and reinforce these skills, such as giving babies rhythm instruments such as drums and tambourines, or putting them on their tummies and having them try to grab toys that are just out of their reach (forcing them to stretch and crawl). Basically, anything that encourages the baby to move in a precise way is a good activity for him.
Language is another key skill that babies need to learn. Most babies babble a lot, so you can create activities to emphasize the purpose of this babbling (communication). One way to do so is to just chat with them: get right in a baby's face and just talk away, putting his fingers on your mouth so that he can feel the way it moves when you make noises. Other mouth games such as peek-a-boo and blowing kisses are also fun for babies.