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.
A child's baby teeth (primary teeth) begin to loosen and fall out to make room for permanent teeth at about age 6. The first baby teeth to fall out are typically the two bottom front teeth (lower central incisors) and the two top front teeth (upper central incisors), followed by the lateral incisors, molars and canines. Molars typically fall out between ages 9 and 12 and are replaced by permanent teeth by about age 13. Baby teeth usually stay in place until they are pushed out by permanent teeth. If a child loses a baby tooth early as a result of tooth decay or an accident, the teeth beside it might drift into the empty space. Teeth in the opposite jaw might also move up or down to fill the gap.