It's holiday time and Miss Beadle wants all the class to gather leaves for a project while they are away. Mary and Laura are particularly excited because the Ingalls family are going away camping and that means they will have access to different leaves to their classmates.
Upon hearing this news, Nellie insists that the Olesons go along as well as she doesn't want Mary and Laura to have a better leaf project than she does. Reluctantly, and mainly for the sake of poor Nels, who definitely needs a break, they allow the Oleson's to tag along. Naturally, Mrs. Oleson pretends to be far superior at outdoor pursuits than she actually is and takes the credit for Caroline's work. Meanwhile, on the leaf hunting expedition, Willie manages to find some poison ivy, which he proudly shows to his mother and, of course, by morning, they are both covered in nasty, red, itchy welts, which Caroline treats for them.
A very funny episode and good to see Mrs. Oleson getting some of what she deserves for a change as it's quite rare!