Simplifying rules

After the talk I had with my son the other day, I suggested that he ask his teacher the same questions he asked me. I was disappointed to learn that the response was: "sometimes authors (who begin sentences with and) forget the rules." This was not what I was hoping for, so I sent a gentle letter to school (my wife insisted on editing it to ensure gentleness). I received the following response:

Thank you for sharing your expertise! You certainly know the rules thoroughly!
For grade 2, to simplify things, we generalize that we use 'and' once in a sentence, as a joining word or part of a list. Also, to reinforce the idea of joining words, not to start a sentence with 'and'. Certainly as they enter older grades, refinements as to the use of 'and' and 'but' will be made.
Thanks again for sharing!

I'm glad to learn that she views this as a simplification rather than a real rule. As I said last time, I don't believe it's a needed simplification because I feel confident that a seven-year-old can understand that you can use and at the beginning of a sentence as long as you don't do it too much. I'm also less sanguine about the chance of refinements being made in future grades. Most of the students (pre-service teachers) in my current TESL class came in believing in a no-sentence-initial-coordinator rule, and in some cases I haven't been able to overcome a lifetime's faith in it.