You could use cubes to make the sticks yourself, or draw the sticks
on squared paper.
If you line up two blue sticks, can you make a line of red sticks
which is the same length?
Try with three blue sticks - can you make a line of red sticks
which is the same length?
What happens when you try four blue sticks? Five?
Andrew decorated 20 biscuits to take to a party. He lined them up and put icing on every second biscuit and different decorations on other biscuits. How many biscuits weren't decorated?