While there are many different sizes of grand piano, they all share the same basic design. Their frame and strings are horizontal rather than upright, with strings extending away from the keyboard using gravity to return action to its state of rest. Covering a range greater than seven octaves, the grand piano also features 3 foot pedals that can be used to change the instruments' sound. Invented at the end of the 17th century, use of the piano was widespread throughout Western society by the end of the 18th and remains one of the most popular instruments to learn, as it is believed that piano lessons help teach children concentration and self-discipline. The individual pieces are simply popped out of the two metal sheets and assembled without the use of solder or glue by simply bending and/or twisting the connection tabs. A metal base (to be assembled) comes with the model to hold it aloft. Assembled, it becomes an authentic, museum-quality laser cut replica of a grand piano.