Whether electronic or paper, portfolios are more than a scrapbook, and not merely a container for storing and displaying evidence of a teacher's knowledge and skills. A teaching portfolio, like an artist's portfolio, is a collection of work that illustrates an individual's talents as an educator (Doolittle, 1994). A portfolio creates a context for teaching experiences. It allows a teacher to analyze his/her teaching, to gather evidence that supports identified beliefs/standards, and to develop reflective rationales that connect teaching and learning. A teaching portfolio is a structured collection of evidence of a teacher's best work that is selective, reflective, and collaborative, and demonstrates a teacher's accomplishments over time and across a variety of contexts (Edgerton 1991).

Traditionally, teacher evaluation is conducted by an outside source: an administrator, department chair, or other supervisor. In most cases, the evaluator spends time observing the teacher and discussing their practice with the individual. This provides the evaluator with a snapshot of a teacher's practice-and while the teacher might play a role in the process, often the evaluator is in control of the situation. Portfolios provide for more than a snapshot-in fact they act as a series of snapshots over time-to provide an authentic context for the teacher's interactions and relationships with the students and the content, thus providing a dynamic, reflective experience for the portfolio developer.

Portfolios allow individual teachers to identify standards, develop rationales for their selections, and provide evidence over time that the standards are being met (or exceeded). The portfolio developer is also the primary evaluator-reflecting upon their own personal and professional growth through their artifacts and rationales. The reflective component of the portfolio provides a structured approach to critiquing and evaluating one's own effectiveness as a teacher (Doolittle, 1994). The type of portfolio described here provides documentation of the unfolding of teaching and learning over time, combined with the opportunity to engage in analysis of what the teacher and students have accomplished.

Portfolio assessment differs from other types of assessment, not only because it is coordinated by the teacher, but also because:

• it allows for selection of multiple sources of evidence
• is gathered in authentic settings
• requires decision-making on the part of the developer and can be used to set and track
• future professional development goals.