Answering the relevant questions here will help you define the particulars about your students' portfolios:
Used for instruction?
Used for assessment?
Used for documentation?
Used for evaluation?
Contents defined by student?
Contents defined by teacher?
Contents evaluated by student?
Contents evaluated by teacher?
Viewed as a resume?
Viewed as a representative sample of overall performance?
Viewed as a constantly changing exhibit?
Used to show evidence that a standard has been reached?
Used to show progress over time?
Used to show student’s interests and abilities?
PDF version for printing .... RTF version for revising