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.
First Tooth. Most babies get their first tooth somewhere between 4 and 7 months of age, although this can vary greatly. A small few children are actually BORN with teeth and some take upwards of a year to see their first one sprout. The bottom two teeth are almost always the first two to come in.