Question: Is it OK to teach to an assessment?
Answer: Yes. In fact, teaching to an assessment is an effective practice. When I teach, I look at what students are supposed to learn, develop an assessment, and teach to it.
Question: So, should I teach to all my assessments?
Answer: That depends. Are your assessments worthy of being taught to? If so, teach to them. If not, change your assessments so they are worthy of being taught to, and then teach to them.
Question: What does a worthy assessment look like?
Answer: Here is a sample essay prompt from English 10: Using the poetry analysis skills we practiced, critique the lyrics of a favorite song (what the lyrics say, how they say it, and what God might think of what they say).
Bottom line: Make sure your assessments are worthy of being taught to—then teach to them.