Having put all three of my children through Montessori pre-school, I became very familiar with a work called the One Hundred Board. It is a very simple wood board with 100 tiles that are numbered. Using your cotton rug, lay the board on the rug and place the tiles with numbers facing up on the rug. Help your child put the numbers in order from 1 to 100. When I first started with Sophia, I only put out the first 10 tiles. Then I added another 10 and so on until she could complete the entire board. It also comes with an answer key for them to match to which is very helpful in the beginning. We also use this to help learning to count by 2, 5 and 10!