Charles managed to fill out his potty card with all five stickers. In response, Mom bought him a new Gordon train engine and tender (the tender turned out to be a mistake). Charles was very happy with it. I made him give Mom the filled out card in exchange for the engine, to try and impress on him the connection between the two events. I’m not sure anything pentrated except “I got a Gordon!”. We’ll see how fast the second card fills up.