These reeds are often found near rivers or streams. Locate the reed and pick one.
Known as snake reed by my children, it looks like pieces of reeds hooked together.
Pull off the longest piece of reed found at the end. Look inside. One side is blocked and the other side open. Rip off the blocked end so that when you look through the reed you can see through it. Press the other end of the reed together and put this end into your mouth, keep the end pressed together while you blow through the reed. Each reed whistles slightly different. It took me 3 tries to get one to actually whistle. I had to put it further into my mouth than I expected.
The kids thought it was great and whistled them all the way back to the car.