Using Manipulatives in the Foundations of Arithmetic

Manipulatives are objects that can be handled and moved. These range from everyday items such as buttons and shells, to resources like abacuses, Cuisenaire rods and Dienes blocks.
Research in teaching arithmetic to young children suggests that manipulatives can support mathematical development. However, the most effective ways to use manipulatives are not clearly understood by teachers, and so they are often under-used.
http://www.nuffieldfoundation.org/using-manipulatives-foundations-arithmetic