Constructivism in 30 Seconds

One popular theory of how we learn is called constructivism.
Like the word suggests constructivism says that learners construct meaning in their brains as they are taught or as they interact with the world, and the way that a person constructs meaning is determined by what is called their scheme, which is a combination of their prior experiences, beliefs, and memories.
This is very different from other views of learning which might treat the learner as a lump of clay for the teacher to shape into whatever knowledge is desired or as a robot to be programmed.