Geo is going to play with a rocket-ship, Milli has a boat, and Bot is playing with a clown, and at the start, you pick with which of these characters and items you want to interact with at the carnival.
Of course, your goal is to use shapes such as triangles, squares, or circles, and many more, to create these items, so you take the right shapes from the right and place them over the model where they match it, and this way you not only build the item but learn how the shapes go together.