Be research-able
Be complex
Connect a main topic to a sub topic.
Allow you to learn something new.
Have a best answer rather than an obvious correct answer.
Can't be answered with a simple Google search
Goldilocks EQs:
Not be too broad or too narrow
Not too hard or too easy
Not be too disturbing
The answers to these questions become the evidence that you use to answer your essential question.
They usually have a correct answer
Who...?
What...?
When...?
Where...?
How questions that measure where the answer will be a number (i.e. How much...? How far...? How heavy...?)
Questions words where there is a yes or no answer (i.e. Do...? Are...? Is...? Did... ?)