Using portfolios for assessment
Portfolios, in assessment terms, are collections of students' work that demonstrate what they have learned and are able to do over a period of time. Portfolios can be kept in folders, binders, large envelopes, boxes or any other containers that allow students to organize their collections and show a diverse collection of work.
What can go into portfolios
Portfolios have always been a way of showing off one's best work in art, graphic design and architecture classes, since these subjects are highly visual. In science, it's a bit trickier to use the portfolio method to best advantage. Since the ultimate goal of the portfolio contents is to demonstrate learning and skill acquisition, it is often helpful to include pieces from the beginning, middle and end of the school year. For example, you might want students to keep samples of how they graphed data, how they wrote up investigations, and how they displayed their findings throughout the year. It is particularly informative to have samples of fair tests that students designed and carried out themselves, to track progress in formulating testable questions and identifying and manipulating variables.
There are a number of ways of evaluating a student portfolio. You can assign numerical values to the different pieces, with varying point levels depending upon completeness, accuracy, originality, etc. You can also evaluate the portfolio as a student-selected collection of pieces that show how he or she moved from initial understanding of concepts to more complete understanding. In those cases, it is advisable to ask the student to explain, either orally or in writing, why these pieces were chosen and what they show. You can then link the portfolio score or grade to both the portfolio itself and the explanation for its contents.