Please remember that this portfolio can easily be used to show your potential employers and/or admissions counselors at post-secondary schools your body of work through your high school career.
If you work diligently through your four years of high school on your own portfolio and place examples of your best work in the portfolio, this may well be an exceptional tool for your own understanding of where you are headed, in career goals and educational goals, and a great tool to show others why they need to take you in their programs as you prepare to move on to the next level after high school.
You may find additional resources about building your portfolio in the two links below: