An experimental group is the group in an experiment that receives the variable being tested. One variable is tested at a time. The experimental group is compared to a control group, which does not receive the test variable. In this way, experimental groups are used to find answers in an experiment.
1 At around 9 months of age, babies begin to pull themselves up to a standing position. 2  By 10 months of age, a baby should be able to grasp objects with thumb and forefinger.
developmental psychologist. Your child's ability to recognize different colors heats up at around 18 months, the same time he begins to notice similarities and differences in shape, size, and texture. But it will be a while longer before he's able to name the colors; most children can name at least one color by age 3. In the meantime, though, he'll love to practice, adding new colors to his mental palette.