"Young children are just learning to move in space.  When early childhood teachers design spaces completely surrounded or enclosed by furnishings, children's ability to move about freely is limited.  Because these environmental structures (i.e., cabinets, shelving units) do not allow children's freedom of movement, they may result in physical ­challenges such as being unable to avoid a classmate's block tower or accidently bumping into others playing in the same space....

"Effective design of classroom spaces and structures takes into account children's ages and stages of physical development.  Appropriate infant and toddler spaces, for example, include a balance of hard and soft surfaces for children to practice rolling, scooting, crawling, and toddling.  Since baby walkers, jumpers, and activity centers confine children's bodies and could possibly thwart physical development, they should not be used."