The essential question is the driving question behind an inquiry-based lesson. It should connect the identified concepts and provide the framework for student investigation. Essential questions should do the following:
Have no one right answer
Involve thinking, not just answering
Help students make connections to past experience
Require students to make decisions or to develop plans of action
Make connections to past experiences
Not be “What is...?” questions
Lie at the boundary of what is known and not known
Be intriguing, mysterious and motivating
Require students to think at the higher levels of Bloom’s Taxonomy
Have answers that students cannot simply look up and find (students must apply research to construct original answers).
Check out the online resources that look at essential questions and strategies to help aid development of essential questions.