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.
Most babies will have their first tooth poke through at any time from 3 to 9 months of age; this can vary greatly, however, so don't worry if your baby begins cutting teeth later or earlier. Babies usually get their teeth in pairs, and the first teeth to appear are the lower central incisors. The bottom teeth will be followed by the upper central incisors, lower and upper lateral incisors, first molars, canines and second molars.