What you need:
A clean wooden stick, Water, Sugar, A clothespin, A tall, narrow glass jar, A pan, Food colour (optional), Paper towel
What to do:
Heat water in a pan. Bring it to a boil. Ask help from an adult for doing this. Keep adding in sugar to the boiling water one spoon at a time. Wait for one batch to dissolve before you add the next spoon. There will come a time when no more sugar can dissolve into the water. Stop adding the sugar then and allow the water to cool down.
Dip the wooden stick into the sugar solution and then roll it in some sugar (on a plate). Let it dry completely.
If you want, add food colour into the solution, the darker the better.
Pour the sugar water into the glass jar filling it almost to the top.
Clip the stick to the clothespin. Let the pin rest on the mouth of the jar as the stick is submerged into the sugar water. It should hang straight without touching the sides of the jar. Leave the jar undisturbed for a week. You can keep monitoring it though. Cover the top with a paper towel to keep dirt out.
Sugar crystals start to grow on the stick. By the end of a week, you have candy on a stick! Why? You made a super saturated' solution when you mixed sugar into the water until it could hold no more. Heating the water added to its capacity of letting sugar dissolve. But once the water cooled, it could not hold that much sugar. So it started forming crystals again. More crystals form as the water evaporates.
The reason these crystals form on the stick is because the stick already had some sugar crystals on it which acted as 'grabbing points for the other crystals.
Picture Credit : Google