I am from group four and I have a daughter who just turned one years old.
Begins to have a sense of separate self, grows 10-12 inches, triples birth weight, can move hands in a rotation that can turn knobs, says first words, and uses whole-body motions at this age/stage.
Babies often do this to express emotions, for example: to let you know when they are hungry or when their tummy is upset.
Distinguishes between voices, smiles, rolls over, and discovers feet at this stage.
Babies often have this unique, indescribable and unbreakable bond with their parents that starts forming immediately at birth, and continues to grow stronger throughout infancy, and life.
Includes curiosity, the ability to perceive and think, memory attention span, general knowledge, and problem solving and analytical thinking, etc.
Includes gross, fine, and perceptual motor activity.
Has a genuine laugh, sees and grasps objects, and makes smiles of recognition at this age/stage.
Bonding begins, motor activity is mostly just reflexes, they respond to mother's voice, and they are aware of senses at this stage, especially pain.
Based on the principle that all areas of human growth and development are integrated.