A pre/post-test is only one example of a diagnostic. Diagnostics can also be useful when not used to gauge student improvement.
As an example, diagnostics such as concept mapping can help teachers to identify gaps in student mental frameworks. Ask the students to map out what they think of when they hear the word “ecosystem”, for instance.
Minute Papers, while often used for formative assessment, can also be a diagnostic. Have the students write for one to two minutes on what they know about a certain subject, or have them respond to a given prompt. Before a history segment on Spanish Flu, for example, you might ask the students a question such as “How can a community prepare for a crisis?”. Before a segment on consumer trends, you might ask a question such as “Where do trends come from?” Reading these responses will help you understand how the students currently conceptualize what you are about to teach and help you direct your instruction.
Next: Formative Assessment