PHOENIX -- School is out for the summer, but one educator will spend at least one day in the hospital -- she plans to donate a kidney to a friend and former co-worker.

Cindy Hans and Marti Klein have been friends for 15 years; they met while working at Mountainside Middle School in Scottsdale.

Klein has polycystic kidney disease, where cysts grow on the kidneys, which causes them to fail. She has been on dialysis for 9 months, and when she needed a kidney, Hans volunteered.

"I've always believed there is risk in life," Hans said. "There is risk when you get out of bed or when you don't. There is risk in seeing your friend suffer. I was fortunate to be able to be an organ donor."

The surgery is scheduled for Tuesday at the Mayo Hospital. Klein will spend a few days in the hospital after receiving the kidney; Hans will only spend one day in the hospital.

"'Thank you' is so hollow," Klein said. "The words are so hollow when it comes to something like this. (It's) just, it's incredible. I don't know what to say."

The two women are already planning their one-year donation anniversary, and they said they're thinking of taking a trip to Sedona.