The dangers of tasting (and testing)

I'm not much of a cook, but I do know that you can't stop to taste the food too often.  For one thing, there'll be nothing left to serve.  Not to mention you'll make yourself fat, or possibly sick (on raw food).

It's the same with testing what your students have learned.  When you stop the class to administer a test, that time is taken away from learning.  Plus, you might be seeing the results of an intermediary stage which won't tell you what the final results will be.  Cookie dough doesn't taste much like cookies.

A good cook uses other ways to check how the food is coming: texture, color.  Imagination.  Guesswork.  Basic knowledge of kitchen chemistry.  

Good teachers also know how to use alternate forms of assessment, from informal hallway conversations with students, to class discussion, to more formally assessed portfolios, artwork and other assignments.  The really good teachers know how to make assessment a part of the learning itself.