Metaphor is one of the most powerful tools available to teachers.
I was talking with a friend and former colleague, Mark. We met when I was at NeXT: initially, he was one of my customers; he later came to work at NeXT. Among the other Insanely Great™ experiences I had at NeXT, I taught a very advanced class on our network administration system, NetInfo. We delved deeply into the bowels of the system: concepts, architecture, IP underpinnings and broadcasting (along with a side trip down netmasks—including non-contiguous netmasks—and routing), SunRPC, and on to the packets on the wire with some real-time sniffer trace analysis.
Part of the architecture includes a newly booted node finding it’s “parent” NetInfo server: a server for the parent domain in the domain hierarchy. My son was somewhere around 4 years old then, and Are You My Mother by P.D. Eastman was among our favorite books. The book relates the story of a little bird who, having fallen from its nest, goes in search of its mother. The bird, not knowing what its mother looks like, nor realizing that its mother would look rather like itself, asks each animal it sees, in turn: “Are you my mother?” It struck me that, though we were talking about a “parent” server, I could cast this as the newly booted NetInfo node looking for its “mother.” I incorporated the nomenclature, and the book, in my class, and drew the analogy of the NetInfo client searching for its mother on a network with a number of potential NetInfo parent servers. To me, the classic, defining dialog from the book (thanks in no small part to another good friend’s having introduced the book to me with this dialog) is:
“Are you my mother?” [the little bird] said to the cow.
“How could I be your mother?” said the cow. “I am a cow.”
Fifteen years or more later, Mark related that every time he reads Are You My Mother to his children, he remembers the class. Apparently, the metaphor struck home, and helped cement the idea of the node looking for its parent server. At the very least, it was memorable!
Metaphor won’t replace a teacher’s being knowledgable. Metaphor won’t replace a teacher’s being experienced. Metaphor won’t replace a teacher’s truly caring. However, metaphor, backed by knowledge and experience, and coupled with caring, can result in a long-lived and powerful learning experience.