In his theory of cognitive development, Jean Piaget explains cognitive structures in terms of _________.

The correct answer is Schemas.

Jean Piaget, a pioneering Swiss psychologist, introduced a comprehensive theory of cognitive development that explains how children construct a mental model of the world.

Key Concepts in Piaget's Theory:

1. Schemas: Piaget defined schemas as basic building blocks of intelligent behavior—mental frameworks or concepts that help individuals organize and interpret information. As experiences occur, this information is used to modify, add to, or change previously existing schemas.

2. Assimilation & Accommodation: Children adapt to their environment through assimilation (fitting new information into existing schemas) and accommodation (modifying existing schemas or creating new ones in response to new information).

Why other options are incorrect:

- Psychological tools: This concept is associated with Lev Vygotsky's sociocultural theory of cognitive development, referring to symbolic systems like language, writing, and counting systems that mediate thought.

- Stimulus-response association: This is a foundational concept in Behaviorism (promoted by theorists like B.F. Skinner and Ivan Pavlov), not Piaget's cognitive constructivism.

- Zone of proximal development (ZPD): This key concept was introduced by Lev Vygotsky, describing the distance between what a learner can do without help and what they can do with guidance and encouragement from a more knowledgeable peer or adult.