6 - 12 years old
During these years your child will change slowly but surely; gone are the rapid development days of infancy, and puberty is still yet to come, so progress will be measured and steady in every aspect. Physical and mental attributes will vary quite widely amongst children even of the same age in this category; expect to notice large differences in height and weight between children of the same age-group.
Fine motor skills will also vary between individuals, but will usually improve with age steadily - things like handwriting or other fine work, for example. Greater motor skills are usually strong and skilled - for example running, jumping, and climbing, but endurance and strength will again vary from child to child.
Children in this period will begin losing their baby teeth and their adult teeth will start coming through, and most children will have all or most of their adult teeth by the age of twelve.
Speech and language skills will improve steadily in these years: children will go from knowing intermediate sentences and thinking, to developing much more complex linguistic patterns and be able to hold conversations with their peers for potentially hours at a time.
At age six, children will enjoy playing with members of the same sex, but do not really form continuous "best friends" until roughly nine years of age. By age twelve their inner social circle will be quite rigid, their outer circle will be quite fluid, and there will usually be one or two peers that each child dislikes intensely.
If you have any concerns regarding the development of your child, always consult with medical professionals - some children take a while to catch up, then really blossom, but others may benefit from various methods of intervention.