Make out of a few flat stones and gel pens a quick number-quantity-sorting game. Allocate the number to the right quantity.
For younger children it probably makes sense, to keep the design on the stones a little simpler. The Montessori principle of isolation of quality would be met and the children are less distracted. You can let loose a bit more on the design for older children - I could not keep myself - and create glowing stones which magicly draw the children in to explore and compare.
- 20 as flat as possible stones in different sizes
- gel pens or other pens (I have tried the ones from Sakura, which definitely need to be varnished - I wanted to try the pens from Posca next)
- Varnish spray other pens, than the ones I have used, might be okay to be varnished with a brush, my pens smudge)
Clean the stones and sort them according to form and shape - the bigger numbers need larger stones of course.
Draw with the gel pens the patterns and numbers on and let it dry.
Spray with varnish. - Done.
As an alternative or addition you can make with the longer stones a domino game.