From Peppa's house get in the car and drive to Playgroup.
Once you leave the car walk to the right and go to the playground where there's a tree next to a sand pit.
Interact with the tree and you'll find a tortoise in the tree (don't ask...) so your next task is to get the teacher.
Run left and go in the school and talk to Madame Gazelle on the right of the room. You'll be whisked to the tree and be tasked to find a ladder.
Go BACK to the school and interact with the ladder for the trophy.