The annual Figment art installation opened on Governors Island in June but the art work, including many pieces designed for children, will be there for the rest of the summer, including a tree house with art pieces, which is back for its third year. The house is made from old doors found on Brooklyn streets. The seesaw piece, “Scratching the Surface,” by Michael Borowski, right, scoops dirt when two people push and pull at either end.