My son, E, is 2.5. He has recently started asking me about letters and numbers, as in 'What is this? This is a number 1.' I'm not ready for this yet. I'm more in the camp of let the children play, there's lots of time for formal learning later on. However, I'm also a firm believer in following the child's lead and this seems to be what my kid wants to know right now. So in the spirit of that I've got several projects on the go which will introduce numbers, the first of which is wooden sandpaper numbers. I think these are great for him as they are larger than traditional sandpaper letters and are fully manipulative. Still Montessori in that they are self-correcting: they only stand up on the base of the number and the correct side is easily identifiable as it's covered in sand. The sand also contributes to the sensory appeal of the numbers.
I ordered the unfinished numbers on Ebay. These are MDF but you can also get them made of pine (which are the ones I meant to order - oops!).
I divided them into even and odd numbers* and then painted each set with different coloured paints I already had. I only painted the sides and the back, leaving the front of the number bare. These took about an hour to cover in two coats of paint. I then left them overnight to dry.
I painted the front of each number with wood glue and then dipped in a shallow pan of play sand to coat evenly.
The thin coat of sand left a very fine finish (too delicate for my toddler) so I left them to dry and then applied another coat of glue and sand.
The finished numbers!
On Monday I'll put numbers 0-4 out in a basket for exploration. Depending on his level of interest and how he interacts with them, I will introduce the other numbers over time.
And there you have it! DIY Wooden Montessori Sandpaper Numbers
UPDATE: E is enjoying the numbers. He likes to stand them up, face them the correct way and tell me which number it is (though this is very hit and miss). When he is able to reliably recognize each number we'll move on to lining them up in order. This is assuming that he is still showing a keen interest in numbers. If he isn't I'll simply rotate them out until he is interested again.
*I'm not introducing him to odd and even numbers at 2.5 - I'm just planning ahead!