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.
Your baby may start learning to crawl when she's between six months and nine months old. By the time she's a year old, she's likely to be crawling well and exploring her surroundings (NHS 2013a, Sheridan 2008) . Bear in mind that some babies never crawl and get around by bottom-shuffling instead.