You can do everything by the book and still have the kids fall apart. Your lesson can look perfect and the kids can learn nothing. Your lesson can look like a disaster but actually be successful. And sometimes there is no way to know how it's going to turn out.It's hard to accept the idea that so much is up in the air all the time, that we control so little in the classroom. And that is a major challenge, but it is also part of the joy. Getting to know our students, learning their personalities, needs, interests, talents, styles and such is the key to teaching them well. Doing all of this takes time and energy, things teachers may have very little of.
There's no panacea. We do the best we can everyday and when we screw up, we start over, giving our best again.