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.
Babies' teeth begin to develop before they are born, but in most cases don't come through until they're between 6 and 12 months old. Most children have a full set of 20 milk or baby teeth by the time they're three years old. When they reach five or six, these teeth will start to fall out, making way for adult teeth.