This string contains 20 beads alternating five white and five red. They come on a blue string which enables them to be moved around easily but not loosely. They are an excellent resource for appreciating the numerical structure of twenty using the key consideration of the quantity of five. Use of this resource would enable weaker students, who are liable to persist in individual counting above ten, to use the cluster of five as a stepping stone to numbers above ten. The boundaries of five, ten and fifteen are so clearly demonstated that number visualisation is enhanced.