I know that this is American and as such may be a little different in the technical language used, but it is such a simple concept to introduce into your maths classes and to develop over time. Its very concrete as in getting the children to manipulate the object so will fit beautifully into the 8 Ways of Learning. This is multiplication by using multiplication, not just by using repeated addition which is what many of us were/have/are taught/teaching. And more than a set of rote learned times tables. Highly recommended.