To carry out these collars, a drilling machine is needed imperatively. To bore in advance 2 holes in the shells and one in the cork stoppers. To take fine rubber band and to thread the large central shell. To reproduce each side of the shell the same continuation of pearls (good exercise on symmetry at the same time). The pearls are proposed to the children in limp with certain colors: they know that they cannot associate all the colors (if not, they are very tried by the multicolor and one moves away from the style “prehistory). The majority of the pearls are out of wood, and the children are invited to put many pearls known as “natural” (color “drink”).