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.
Although a few babies are born with teeth already in place, the age that babies start teething is usually at around six to nine months old, though all babies are different and the timing can vary a lot. We have put together a rough guide outlining the different stages you may expect your baby to go through.