Two twin parts (1) comprise the sides of a piece of furniture and are joined together by an odd piece having no pair (4) and by pairs of parts (2) and (3). One of the lengthwise sides of the parts (1) configures the supports (7) which comprise the legs of this piece of furniture when being used as a table, whilst the opposite lengthwise part comprises a convex arch (8) which comprises the support for this piece of furniture when to be used as a seesaw. Parts (2) and (3) comprises the seats of this piece of furniture, and part (4) comprises the playing surface of the table and the footrest of the seesaw.