The Red Rods used in a Montessori Classroom are a set of 10 prismatic wooden rods. These vary in size from the shortest (1st) to the longest (10th).
By working on Red Rods children learn Visual Discrimination as well as Gradation from the longest to shortest or vice-versa. In a beautiful way it helps children develop skills of Alignment, Order and Focus.
It also enhances their vocabulary with Degrees of Comparison like long, longer, short, shorter.
The interesting thing here is that the learning is not confined to just this level but rather forms a base for learning the advanced and the most significant concept of Math Numbers from 1 to 10.
The possibilities with the Red Rods are endless as children can do Equivalence (using two short rods to equal up to a longer rod), make different Patterns like the Sun, Mazes and others which may reflect the children's creativity :)