Both 2D and 3D? I have plans to do animation classes all throughout High School and College (if I keep my grades good! I'm in my second semester of freshman year with five credits)

Most likely 3D animation is what I'll be doing, unfortunately, I've got no free program to get me started yet :/ however, I've animated with 2D animals in the past (not the greatest animations anyone has seen, but it was a start) I got into my interests with it when I began to study the movement of the animals in TLK and Balto. More of TLK because at the time of when I started, Balto character (the dogs) seemed....stretchy.

I'd look into classical 2D Disney movies and recent 3D movies if you're studying animals and humans alike. I'd take classes regarding art and graphic art.

What to include would be beginning concept art to finished products, or anything along those lines. I'd also include lesson files on 'movement' or something like that. That's just what I suggest.

Hello, I am an animation major in college currently. My classes didn't require a portfolio the same way yours apparently does, but I did pass the bachelor of fine arts review to make my major official and allow me to continue in my art courses.

I had a mix of stuff in my gallery setup for the review from a six-foot tall graphite drawing of a Blaziken's skeletal system to photos of a blanket I had made from weaving strings of lifesaver mints together. The animation I entered was my visual take on a story narrated by a man about a tragedy he had experienced and how he moved on.

Animating a short story like that can be very impressive, you just have to make sure to cite your sources correctly in the credits. I can give you the site where you can find different audio narrations if you are planning to animate something for your portfolio. Assuming you have a way to animate, making a walk or run cycle is also a good way to show your ability.

If you don't have any way to animate something then I would suggest including your best still life drawings and life drawings, and don't just use graphite, try charcoal and other mediums as well, painting included. You basically want to show them that you know enough about form to make believable animations. I don't know exactly what they are looking for, but character studies/concepts could be helpful if it's specific to animation.