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.
When Do Babies Start Smiling? Babies will often exhibit their first smile between 6-8 weeks of age. However it is not uncommon for your baby to smile before or after this time period either. Your baby is looking for ways to communicate with you from the moment they are born and they are capable of learning quickly.