There is a difference between foolishness and childishness. Foolishness is a biblical anthropological description of a child's heart. Childishness is not directly mentioned in the Bible, but is a description deduced from common study of childhood behavior. Childishness is associated with innocent immaturity, the honest mistakes children make. Foolishness needs correction but parents should not correct all foolish behavior the same way, or with the same consequence.
Biblical discipline begins with parental instruction.
When we consider the role of instruction in a child's life, there are a few facts and elementary principles that serve as a guide to success for all of your parenting years. When you speak to your child in a way that requires an answer or an action, you should expect an immediate and complete response. Children will rise to the level of expectation of their parents. Too many parents expect less and receive exactly that. We find consistently that the requirement of first-time obedience is far less of an adjustment for children than it is for their parents.