Lizzie is looking forward to the science class field trip, but she is mortified when she finds out that her mother is a last-minute replacement as the girls' chaperone. Lizzie fears that her mother will embarrass her to death, and Mom does a pretty good job of doing just that while they are competing with the boys on a nature walk. But Mrs. McGuire proves how cool she can be when she helps the girls get back at the boys for a prank they pulled then takes all the blame herself. Back at home, Matt and Mr. McGuire are left on their own and try to cook for themselves.