Keep it simple. Assemble the ingredients in the following fashion. Put together as much of the pole as your child can handle but no more. If your children are only four or five years old, then perhaps only the four foot tip section will be suitable. A ten year old, on the other hand, may be able to control the 12' length of the three sections together.
Versatility is the advantage of using sectioned bamboo poles.
Now, take the braided dacron line and tie the end securely near the fatter end of the tip section. A series of granny knots or square knots will do if you wind the line around the pole a few times first. Then spiral the line up to the tip of the pole and add a half dozen half hitches here. When this is done, if the tip breaks off, you will still be able to pull in the line with the rest of the pole. Taking the spool of line in hand, spiral the line back down around the pole all the way to the butt and add six inches for good measure.