Listen to Dylan Wiliam describe formative assessment in its most general form.Â
What information am I collecting about my students achievement?
Is this information high or low stakes?
On the fly, while teaching, am I aware of my most of my students' correct thinking, misconceptions, and half-conceptions?
Do I have the time to respond and make (or help the student make) adjustments if the learning is not on track?
 Here is Dylan Wiliam and Paul Black's work on formative assessment.