D.W. Thinks Big is the first part of the 25th episode of Arthur season 1. It day viewed with Arthur Cleans Up on March 10, 1997.
At Aunt Lucy's wedding, Arthur is the ringbearer and their dramatic diva cousin Cora is the flower girl, but D.W. is too little to do anything. However, when the wedding ring gets lost in the pipe organ at the wedding, D.W.'s size helps her.