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.
Kids have about 20 teeth by the time they turn 3 years old. This first set of teeth are called milk teeth, baby teeth or primary teeth. By the time you are five or six, your first permanent teeth will start coming in. The permanent teeth lie just beneath the roots of the baby teeth.