Shirley Partridge joins an art class and is encouraged by her teacher, Lorenzo Bernard, who says she shows a natural artistic ability. When she shows off one of her paintings to the family, the kids thing it's awful but pretend to like it not to hurt her feelings. When Lorenzo begins coming to the house to give Shirley private lessons, the kids are suspicious about his intentions. They enlist the help of Reuben in getting an expert's opinion on their mother's painting talent. The art expert agrees the painting is bad. But, by now, Lorenzo has talked Shirley into showing her paintings at the annual San Pueblo Art Festival and Shirley is beginning to think she might really have talent. At the art show, the kids devise an elaborate plan to protect Shirley's feelings and not let her see how much people dislike her paintings. Shirley catches them in the act and makes them confess their true opinions of her art work. Shirley decides she's been taking her hobby far too seriously and from now (thetvdb.com)