Paraphrase:

SCT argues that human mental functioning is fundamentally a mediated process that is organized by cultural artifacts, activities, and concepts (Ratner, 44). This suggests that there is a big difference in the development of the child when he/she is in the company of more knowledgeable other.

SCT suggests that human cognition is primarily shaped by cultural influences, such as artifacts, behaviors, and ideas (Ratner, 44). This implies that children benefit greatly from interacting with individuals who possess more knowledge and expertise.