Piaget stressed cognitive development, intelligence, and learning as a function of age. He suggested that children developed step by step through different stages of development. According to him to move next stage children could complete cognitive development steps of former stage. Piaget determined approximate age periods for these stages, however, he stated that stages should be longer or shorter. He claimed that there were four main stages of development which are, sensorimotor(0-2 years), pre-operational(2-7 years), concrete operational(7-11 years) and formal operations(11 years and up). Nevertheless, he claims that every child could not pass next stage before completing former one. In contrast, Bruner emphasised that all knowledge should be thought at every age. However, Bruner gives importance that how the knowledge is presented. According to him, different ways of representation were important at different ages. Like Piaget, Bruner stated that intellectual development occur sequentially through enactive representation, iconic representation, and symbolic representation. However, unlike Piaget's stages, Bruner's modes did not necessarily depend on age. Enactive mode refers using of motor skills. (Julie Mckoy). I think it corresponds with Piaget's sensorimotor stage. At this mode; knowledge is stored by the form of physical actions. Children learn by doing, rather than by thinking. At this mode, physical activities are important such as learning to ride a bike. At iconic mode, knowledge is stored as visual images. For instance we can imagine an empty plate or a plate that is full with fruits. We can think about differences of two situations separately. At symbolic mode, knowledge is stored as words, symbols. This mode includes advanced symbols or advanced language skills and I think it corresponds to Piaget's operation stage. The development of the symbolic mode of representation, particularly the acquisition of language, allows children to think about abstract concepts.