Whoosh! It's a windy autumn day and Stinky is under a pile of leaves. Chris, Elmo, and Rosita dig him out, then Rosita begins to problem-solve, trying to figure out which tree the leaves are from. The friends become leaf detectives, comparing a leaf from the pile with leaves on surrounding trees. Will they find a match? Special guest star Ken Jeong explains the word “deciduous.” Plus, in Bert and Ernie's Great Adventures, there's a frog race, and in Abby's Flying Fairy School, it's opposite day! Finally, Murray experiments with twirlers, and it’s time to learn about the weather in Elmo's World.