Lev Vygotsky was a famous Russian psychologist who lived in the early 1900s. He studied how children learn and develop and came up with the idea that we learn best when we interact with other people. He suggested that when an adult helps a child learn something, it can help the child later on by allowing them to remember and use the information independently. His ideas are often used in classrooms today, with teachers providing guidance and support to help their students learn.