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.
Age 4-7 Months. From 4-7 months of age, babies learn to coordinate their new perceptive abilities (including vision, touch, and hearing) and motor skills such as grasping, rolling over, sitting up, and may be even crawling. Babies now have more control over what they will or will not do, unlike earlier months in which they mainly reacted by reflex.