School kids aren't the only ones that enjoy stacking cups. A sea otter at Point Defiance Zoo & Aquarium loves the brightly colored cups, too.

The zoo released a video of Nellie the otter showing off her cup-stacking skills as she hangs out with her pal, Abra.

You can see otters Nellie, Abra, Homer, Kaladi and Libby - along with E.T. the walrus - at Point Defiance Zoo & Aquarium. Learn more at http://www.pdza.org