Numberlines can provide support and be a model for early work with all four operations. They can be used to aid understanding of sequences of whole numbers, decimals and fractions and as a precursor to rounding. Identifying or placing numbers on numberlines with just the ends numbered encourages thinking about the value of each interval, a skill necessary when reading scales for measuring or in graphs.
Number tracks are similar to numberlines, but contain the number within the interval (which is usually a square). If you buy the Numicon number track, it is compatible with centimetre cubes, such as Dienes (base 10 blocks) and Cuisenaire.