This free math video gives ideas for introducing Cuisenaire Rods. These ideas will work for older children, too, not only preschoolers. These should be done after much time spent in unstructured play with the rods.
The rod numbers are based on length and prepare the child to learn about addition, subtraction, multiplication, division, and fractions/decimals/percents (as well as negatives and algebra with a few cosmetic changes to the rods).