Rods which vary in length, usually between 1 cm and 10 cm, are used to develop children's perception of length and space - essential in geometry. There are a number of activities that children can do, such as use them as primitive rulers to measure a distance set by their teacher or parent. Apart from length perception, children will also familiarize with the concept of place values, initially the tens' and ones' place, when they get to measure distances which require the 10-cm-long part.
Children will be introduced to the decimal quantities of 1, 10 and 100 with matches. This can easily be a Montessori-style, do-it-yourself material, as you can glue 10 matches together to create a square, as well as 10 such square, to make a cube of 100 matches. It will be a way for kids to understand the connection between the basic unit and larger quantities, as well as the geometrical concepts of area and volume.
A cube-shape box, containing smaller cubes inside, is a way for children to understand how physical objects can be divided or assembled. It will also introduce them to the concept of the basic operations, adding and subtracting. Kids will see that an object can be divided in smaller parts, if you remove certain units. Likewise, by adding a specific amount of little cubes, you can create a large one, a notion that will prove helpful during their algebra lessons at school.
Ten compartments, each numbered from zero to nine and a large number of spindles is what you need, to help your children familiarize with numerals. Children can practice, by associating each numeral with the corresponding amount of spindles. It would be better if the activity was done with the help of a parent or teacher who could guide the child through her initial unawareness phase, providing tips such as how to identify a number based on the previous or later numeral.