There are many varieties of wooden number puzzles. We have the Melissa & Doug wooden number puzzle.
1. learn to rote count from 1 to 20
2. learn to recognize numerals 1 to 20
3. learn to put written numerals in the correct order.
I give Matthew the pieces, one at a time, in the correct order so he gets accustomed to the sequence. As he lays the pieces on the puzzle board, he sees that they go from left to right, which is good practice for reading since the English language is read from left to right.
Our next step is to teach him to arrange the numbers in the correct order without the board to match. However, this activity is only meant to teach sequence, not the concept of big or small numbers or quantities.
Note: Some 3-1/2 year olds may find this to be the most boring activity ever. Matthew thinks it's quite fun. It helps that he is currently highly interested in numbers and counting.