Jan, A ‘big’ marble is often called a shooter (or boulder). “Shooters,” in the official tournament rules, must not be larger than six-eighth’s inch in diameter, although most children who played neighborhood games used marbles from seven-eighths to one inch in size for their shooters. The term “boulder” usually referred to the larger sizes of one inch or bigger–but these are often difficult to knuckle down with, for a kid with with small hands.