the sizes of the triangles that we have available are 1/2", 3/4", 1", 1 1/4", and 1 1/2". this program is a great head start for some very bright kids. find all the past winners here. why do some north arrows only have half a head and when they do what does that indicate? the move has been a long-time coming. that is because your head is up your own ***. if you do not want information about you to be shared in this manner, do not use this feature. 