Quick Answer. An experimental variable is something that a scientist changes during the course of an experiment. It is distinguished from a controlled variable, which could theoretically change, but the scientists keep constant. Continue Reading.
While you were pregnant, your baby developed tooth buds, the foundation for baby teeth (also called milk teeth). Very rarely, a baby is born with a tooth or two, or grows a tooth in the first few weeks of life. But the vast majority of babies sprout their first tooth sometime between 4 and 7 months old.
Dental development. All 20 baby teeth usually come in by the time your child is three years old. Tooth eruption varies from child to child. Most children start to get teeth around six months, but it is not unusual for teeth to begin appearing as early as three months or as late as one year.