Cotton had become the largest cash crop. But plantations also grew corn, rice, sugarcane and tobacco. Slaves on plantations may have averaged 50 or less, but the largest plantations had hundreds of slaves. In addition to field work, slaves also were skilled in trades such as blacksmithing, carpentry and mechanics. Domestic slaves did the cooking for the family, raised their children and performed all the work in the household. They were always supervised and had to work at all times they were not sleeping. Domestic slaves had virtually no privacy. Young white children formed close attachment to their black nannies. But as they grew up they were educated as to how slaves were to be treated.