It's field trip day! Elinor, Olive and Ari are going to see some of the tallest trees in the world: giant sequoias. Though the friends expect them to be big, they're shocked by what they find in the forest. They can't even see the top of the largest sequoia! How tall is it? How does it grow so high and straight? And why is its trunk so wide? The friends look for clues to solve the sequoia's mysteries!

Based on the TV episode 'Big trees,' written by Jorge Cham and Daniel Whiteson.