You will need 5 matches.
Broke down in the middle of them, bend at right angles, and put on a saucer.
Put a few drops of water in the folds of matches. Watch. Gradually, the match will start cracking down and form a star.
The reason for this phenomenon is called capillarity that wood fibers absorb moisture. She creeps farther through the capillaries. Wood swells, and his surviving fibers "get fat", and they can not bend much, and start cracking.