Whiskey and Womble take us through the steps to teaching a pet rat how to tunnel fetch (fetching a ball from a tunnel).
Remember to keep the training fun for you and your ratties, don't train for too long each day. Even 5 or 10 minutes a day is long enough. This is a pretty simple trick to teach and they should instinctively learn it very quickly.
Have an iPhone? Check out all 200+ new features coming in iOS 13.