This project is great for kids because it can introduce them to safe use of a small saw and sharp knife as well as looking cool.

The reason we use a stick is because there's already a hollow core which can act as holes for the beads when you cut the stick into small pieces.

Supplies

A sharp knife
A stick (twig)
Some string/thread/wire/twine.
A small saw (I used a junior hacksaw)
A thin object such as a dowel or knitting needle
Sandpaper
Optional: paint
Varnish (wood varnish or clear nail varnish

Step 1: Finding a Stick

When choosing a stick it's best to choose one that has already fallen to the ground and is quite dry already. If you choose one which is too fresh then the beads are likely to split after you make them.
Another thing to consider is the shape and size. The thickness determines the size of the beads and you want to choose a stick which is long enough to make enough beads for the necklace that you want to make.

Step 2: Removing the Bark

Use the sharp knife to remove the bark. Use long paring Strokes away from yourself. Make sure your fingers and thumbs are out of the way of the blade and make sure children doing this are supervised by an adult if they're still learning to use knives, and remember that blunt knives are more dangerous than sharp ones. Whittle responsibly!

Step 3: Making the Beads

Saw small sections off the end of the twig. These become the beads. The length of each bead is up to you. You don't need to accurately measure the length of each one, just try to make them relatively uniform.
Be patient. It's so satisfying when you've made them all.
It's up to you how many you make, depending on the length you want your necklace to be. The one i made here has 71.

Step 4: Removing the Inside

There's no need to drill a hole in the centre but you do need to remove the pithy plant matter from the centre of the twig so you can thread the beads.
I used a thin wooden dowel to poke all the stuff out and this did the trick.

Step 5: Finishing the Beads

You can decide how much you'd like to finish the beads if at all.
Use Sandpaper to remove any left over rough edges from the beads and until they're as smooth as you want them.
Optionally you could paint the beads anyway you want
You can finish them by putting a layer of varnish on them.
It's also a good time to arrange them to make sure you have enough.

Step 6: Threading the Necklace and Finishing the Project!

The final step is to thread the beads onto whatever string you're using.
Once threaded, cut the string and tie a couple of knots. You can thread the loose ends back through some of the beads to finish the necklace.

Your project is finished! I hope you enjoyed making it!