Nothing captures the type of teacher you don't want to have more than Ben Stein's brief cameo in Ferris Bueller's Day Off:

But anyone with classroom experience knows that it's very easy to become this teacher. It's a vicious cycle - when students are passive, teaching becomes passive, which makes students more passive, etc. Breaking this cycle requires a shift in focus - good classroom instruction is less about being able to explain things accurately and more about understanding how students learn and being aware of what they are learning in the moment. This fact is relatively easy to understand, but can take a lifetime to master. As a starting point, here are several tips that you can start to apply in your classroom teaching today.

Don't describe something when you can demo it instead.

Students have short attention spans in general, and studies show that it's far shorter for passive learning compared to active learning. Instead of talking about how something works, it's much easier for them to focus and grasp the concept when they see it in action.

Don't get into long tangents.

Any tangent away from the main concept being taught adds unnecessary cognitive load to the student. It's human nature to want to share knowledge, but good classroom instruction requires restraint on the part of the instructor in this way.

Don't show advanced techniques.

It's tempting to show students a shortcut, alternate approach, or advanced refactoring method when teaching a new concept. These techniques should be taught, but consider it a separate concept altogether - they should only be taught after the student has the basic concept under their belt.

Don't assume that if no one asks a question, everyone understands.

Teachers have the habit of asking "Does everyone understand?" as a way to check for understanding. When no one asks a question, it is often not due to understanding the material, but rather because they aren't able to articulate what they don't know. Try posing specific questions involving specific scenarios to get a clearer picture of what students understand.

Don't assume that if 1 or 2 people answer every question, everyone understands.

If 1 or 2 people answer every questions, the only thing you know for sure is that 1 or 2 people understand the material. You must gather information about the understanding of all students. This doesn't necessarily mean you have to call on specific students when asking questions - there are many good ways to gather these checks for understanding. Asking questions that only a few students answer isn't one of them.

Don't give away the answer to a student's question immediately.

The best answer to a question is with another question. Try to get the students to think through a problem by providing a guiding question that reinforces general problem solving strategies. Again, you should resist the natural desire to share your knowledge - ideally, an instructor's role is not to give knowledge but to lead students to discover that knowledge for themselves.

Don't try to answer all student questions.

Some questions require students to understand several other concepts that have yet to be taught. Resist the temptation to answer every question - it's okay to tell a student that the question will be revisited in the near future.