Super Move, Morgan! — Ted Staunton

Morgan has to spend all of one Saturday with Aldeen Hummel, the Godzilla of Grade Three, so they can make a log cabin for their project. Morgan is upset because he is sure she has taken his Commander Crunch action figure and hidden it from him. Once he sneaks into her room to get it, then he has to deal with the reality that he has taken something that isn't his.
In this latest book in the series, Morgan encounters several awkward situations and has to figure out how to come out unscathed.