Follow the pictorial below so you know how to cut watermelon sticks.
How To Cut Watermelon Sticks
Start with a whole seedless watermelon
Slice in half
Place one half aside, and leave the other half on the board
One half at a time, slice in rows as shown in picture. This will leave you with the traditional half moon slices.
Cut and discard the very ends of the watermelon half. One half moon piece at a time, slice from rind to fruit to cut into sticks.
Can easily be cut many sticks at a time. Mainly it is like dicing an onion. Cut all rows one way, then cut the opposite direction.