Puppy Potty Training Bells!
Hang these bells on your door handle, and whenever you let your dog out, ring the bells with their paw (or nose, as my dog likes to use), and reward them (with a treat, a good ole pet, or their favorite toy. Then, let your dog out and when he or she is finished, reward again. My dogs picked this up very quickly and within less than a week they were ringing it. Order here: https://www.etsy.com/listing/185252561/dog-potty-training-bells-can-be-used-for?ref=shop_home_active_1