to 11, is when children rapidly grow cognitively and drastically improve their basic skills and language. Here, children can demonstrate some abstract thinking although much of this thinking is still grounded by actions. The formal operational stage, which starts around age 11 and goes on to adulthood, is the last developmental stage in Piaget's theory. This stage expands upon the concrete operational stage by using higher levels of thinking such as hypothetical thinking, more developed abstract thinking, and idealistic thinking. Throughout these motivational stages, the mechanism in which the children and people learn, is through a concept called equilibrium. This mechanism is the process where an individual is able to resolve cognitive conflicts by either applying one's beliefs to one's experiences (a process called assimilation) or by changing one's beliefs to accommodate new experiences and information when encountering new situations or concepts. Social constructivism Social constructivism, like its name suggests, believes that knowledge and learning is gained within social situations. Led by psychologist Lev Vygotsky, social constructivism has a more sociocultural approach. This approach argues that the social environment facilitates learning through certain tools such objects, language, and organizations. Through these tools, cognitive learning occurs when the people interact with these tools socially and internalize them. A major concept within social constructivism is the zone of proximal development (ZPD). ZPD represents the potential amount of learning a student can have given the right environmental conditions. This model suggests that the teacher and student work together to further the student's learning. Educational examples of this include instructional scaffolding and apprenticeships where the educator takes an invested and active role in furthering the knowledge of the student. Motivation Various motivational theories play a role in the psychology of learning. John William Atkinson's motivation theory argues that people are motivated to achieve their best. This motivation is in part moderated by two different sources: the desire to succeed as well as the fear of failure. Another motivational theory is Allan Wigfield's and Jacquelynne Eccles's expectancy-value theory which states that motivation is moderated by one's desire for success as well as the importance of the tasks one needs to do. Self-worth theory also plays a role in learning as students and individuals are motivated to learn and achieve because of their desire to maintain their perception of being high achieving. Goal theory is another related theory. Learners usually have two types of goals: learning