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.
When can I expect my child's first tooth to come in? Teething can begin as early as 4 months of age, but most babies don't get their first tooth until 6 months. Teeth usually come in pairs. The bottom front two teeth typically show up first, followed by the top ones (both sets are called central incisors).