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.
The average age for a baby to begin teething is 6 months, although it can begin at as early as 2 or 3 months or as late as 12 months old, according to eMedicineHealth. On average, a child has all 20 primary teeth by the age of 3, reports WebMD.