Many daycare centers separate children by age groups and developmental levels. This can help prevent the spread of illness, as the presence of children in diapers pose a higher risk of spreading diarrheal (die-uh-ree-ull) diseases and hepatitis A. A further plus of dividing children into age groups is reducing the risk of injury to smaller children. Smaller kids often love the challenge of playing with the 'big kids,' but the difference in development can make this a risky endeavor. Many centers group according to age levels because children are generally ready for new skills around the same time. Three-year-olds are ready to begin consistent peer group interaction; four-year-olds are usually ready to start using small manipulatives. States' guidelines for grouping children are generally done according to age groups, and when mixing the groups, most regulations require the child-to-teacher ratio for the youngest child be observed. There are benefits to mixing age groups, as often happens in private home care and Montessori centers. The family home daycare setting can be familiar, and therefore comfortable, for most children. In both Montessori and home care centers, older kids can be given responsibilities to help foster their social development, such as clearing a small child's plate from the table. Here's a plus-- if your child is exceptionally mature for his or her age, being in a group that includes older chidlren can provide needed intellectual stimulation. For more information on group separation, speak to your childcare provider.