A good essential question is key to an engaging and effective unit.  An essential question should have the following characteristic-

S - Synergistic: An essential question should allow students to bring together multiple concepts into something new.

M - Meaningful: An essential question should be relevant and interesting to students.

E - Educational: An essential question should encompass your instructional goals.

L - Lasting: An essential question should have an “answer” that is more important than points on a test.

Here is an example-

Possible essential question: What is the water quality of the creek near our school?

 

A better essential question: How does the land use “upstream” impact the water quality of a creek?