Slice each orange into approximately 16 thin slices (6 if you are using smaller oranges) and set aside.
Bring water and sugar to a boil in a small saucepan, stirring to dissolve the sugar into the water.
Add the cinnamon sticks and the orange slices. If there are any slices that got mangled during cutting or just don't look as pretty (like the end pieces), squeeze their juice into the saucepan.
Lower the heat until you have a rolling but not super powerful boil and cook for 20 minutes, rotating the slices occasionally.
Lower the heat to a simmer and cook for another twenty minutes.
Using tongs, transfer candied orange slices to a cooling rack (if you don't want your counter to get dirty, put a paper towel under the rack). Save the orange syrup left in the pot to use on pancakes, over ice cream, in drinks, or in whatever other way you can dream up.
As soon as the candied orange slices are cool, transfer them to parchment paper. If you leave them on the cooling rack too long, it will be hard to remove them.
Serve candied orange slices as a snack or use to decorate cake, cupcakes, or pie.
To make candied orange slices crispy, use a dehydrator to dehydrate them after they are done.