One of the 'toys' I remember from my Montessori experience was these long bead chains. They had all different sizes, e.g. one would be a chain of 8 segments, each containing 8 beads on a rod between the joints. The '8' chain would be blue and have an associated blue cube of beads 8x8x8. I remember the '10' chain and cube was something really to be seen.

We also had really large blocks, because someone dropped one on my head.