As soon as Arthur's little sister Violet mentions a girl in her class named Sandy, you know that the picture Arthur has requested of Sandy, his karate-practicing pen pal, will reveal them as one and the same. Meanwhile Arthur goes on about how lucky Sandy is to have a big brother instead of a little sister. . . . But the effect of the photograph's eventual arrival is to make him appreciate Violet, who beats him at jump rope but not arm wrestling and who doesn't do karate at all. Those who are warmed by the rosy cast that Arthur and Violet contribute to sibling give-and-take might applaud the sentiment, but we find this their weakest performance so far.