(cheerful music) (electronic gadgets whirring and ringing) - [Children] Math Mights! Welcome, 2nd grade Math Mights. My name is Mrs. McCartney. I'm so excited that you've joined us today for our show.

A 3D shape with all straight edges and flat faces is a polyhedron. Other 3D shapes with least one curved surface are not polyhedra. A 3D shape with regular polygonal faces, meeting at equal angles, is ...