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.
At What Age Do Babies Start Teething? According to the American Dental Association (ADA), a baby's first tooth often appears anywhere from eight months to a year of age. The last teeth to grow in are usually the molar, or back teeth, which often start making an appearance anywhere from 13 months all the way up to 33 months.