This is typical. For example, sometimes a baby may experience many fussy nights just before learning to sit and crawl. Children usually accumulate many aspects of a skill and then practice the skills that they have learned without further learning. The child repeatedly goes over previously learned activities. The plateau period is necessary for the child to perfect the skill being learned.
Physical development changes a child's ability to do things.
Development in motor co-ordination controls the movement of body parts such as the hands and feet. Intellectual or cognitive development refers to the active processes of perception, memory, generation of ideas, evaluation, reasoning, and problem solving. It is the development of the ability to cope with and adapt to new experiences. Emotional development encompasses development of the emotions, such as joy, anger, fear, and surprise. It begins with the development of attachment and later, trust and self confidence.