Alberto is learning algebra. his teacher provides him with classroom instruction and exercises to work at home and also solves problems with the class. when concepts are new, the teacher interacts often with alberto and his classmates, showing them how to perform operations, giving subtle hints, asking leading questions, and making suggestions. as alberto becomes more competent in his new skills, his teacher begins to back off, allowing him to work with increasing independence. alberto's teacher has used the constructivist principle of a. negotiated meaning. b. scaffolding. c. multiple perspectives. d. situated learning.