Danny and Calvin decide to find out why their fourth-grade teacher, Mrs. Cakel, is suddenly behaving very strangely by not only failing to enforce her many rules, but by violating some herself.

Bizzy and Dill decide to celebrate Opposite Day by spending their time doing the opposite of what they usually do, including starting with dinner instead of breakfast, wearing their pajama pants on their heads instead of their legs, and singing a book and reading a song.