I'm introducing to N the concept of measurement. Here's how i do it.
I used my Montessori Number rods and Red rods.
First, we arrange the number rods in order.
I then randomly select a red rod and ask out loud 'how long is this?'. I took a number rod, measure it against the selected red rod and ask N if they were of the same length. When we determine that it was so, N measured the length of the red rod by counting the number rod. We did this for all 10 rods. It was nice to see N having fun with this!