I have waited 15 years to become a Frog and Toad survey volunteer, and I have to say that I have loved every minute of it. I finished my third of three surveys this year. I highly recommend the training even if you don't move on to volunteerism. You can learn the frog and toad calls here at the PWRC website -- taking the quiz is helpful.
I learned about the survey back when we were homeschooling and had a county conservation board class. We learned three frog calls, and I wanted to learn more. There are 17, maybe 18 total, in Iowa, and I have counted up to 7 species on my route.