(1) Intelligent development characteristics (1) Gross motor: can support chest with forearm and lift head when lying down, can balance head when holding upright, gradually can turn over from supine position to side or prone position. (2) Fine motor: can get toys from adult’s hand, can look at their own hands, can grasp toys and put them into their mouths. (3) Visual development: visual ability is more complete, and can gradually focus on distant objects; active visual concentration begins to appear, and visual conditioned reflexes begin to form, such as reaching for a bottle when seeing a bottle; correct color perception, able to look at themselves in the mirror, and have obvious avoidance responses to approaching objects. (4) Auditory development: they can turn their heads happily when they hear a sound; they begin to actively “listen” to music, preferring to listen to pleasant and beautiful music; listening to music is always accompanied by repeated body movements, but the movements and music are not yet synchronized or coordinated. (5) Language development: Talking to themselves, babbling constantly, and responding to adult words. (6) Social interaction: reaching out to mother for a hug and laughing when teased by adults. 2, ability training (1) turn over (side – prone): 4 months old baby can play in the supine unconsciously prone over, sometimes also constantly struggling to turn over, then you can put the baby’s favorite toys on his side, when he wants to get his hands on the toys next to the body, will turn over. At the beginning, after the baby turns over, one arm is often pressed under the body, parents can give the baby some help, slowly train him to put his own hands, deftly turn over, free to choose the posture. Parents should consciously help the baby to turn in the left and right directions, through turning over to change positions, so that the baby change direction to know the world. (2) pull sitting: after the development of prone head-up, turning and other movements, the baby’s neck, forearms and waist and other muscle strength gradually increased, the baby’s initiative to change the posture more and more obvious, at this time you can try to pull the baby to sit up. The specific practice is: baby in the supine position, parents grab the baby’s two small hands, let him cooperate, parents by a little force to help, pull the baby to sit, can do several times a day, after parents slowly reduce the force, training the baby only hold the parent’s fingers can take the initiative to sit up, so you can exercise the baby’s muscle strength. 3, cognition, language and communication Cognition: the baby will adjust the visual focus, can see far or near objects, the ability to distinguish between red, green, blue three pure colors, hearing is also very sensitive. Training methods include: (1) see faces, listen to people, through the distance, different directions, familiar and unfamiliar sounds and faces, etc. to train babies. (2) change toy patterns, toys from large to small, different patterns and types. (3) often to outdoor activities, more contact with nature, animals and various objects, learning visual tracking, rich baby’s audio-visual stimulation. (4) Choose large, brightly colored, realistic and beautiful pictures for your baby to see, and talk to your baby while you watch. (5) Choose beautiful and beautiful sounds of nature or listen to hanyu pinyin tapes to listen to your baby. Be careful not to listen to music with too fast a rhythm or too strong a sound to prevent hearing damage. (6) Train your baby’s ability to grasp toys and train eye-hand coordination. (7) Let the baby look at the rolling ball and make him/her follow the ball, when the head also turns; you can also train the baby to follow the bright light of the flashlight in the evening when it is getting dark.