What is the primary feature of a portfolio in educational assessment?

A portfolio in educational assessment primarily serves as a comprehensive tool that showcases a student's developmental progress over time. This means that it allows educators and students alike to document growth, reflect on learning experiences, and display a variety of work that illustrates skills, achievements, and understanding in a meaningful way.

Portfolios often include a collection of the student's work, such as essays, projects, and other assignments, which can highlight the journey of the student's learning rather than just a final product. This approach emphasizes the process of learning and development, making it a valuable tool for both formative and summative assessments.

In contrast, evaluating performance against peers or summarizing knowledge solely at the end of instruction does not capture the ongoing nature of development that a portfolio emphasizes. Additionally, while summaries of tests taken can inform about knowledge or skill levels at specific points, they do not provide the holistic view of a student's growth that a portfolio does.