Leo loves using sign language. My son is 19 months & he started using sign language at about 12 months. This is the book I use to teach my son sign language. I start the day with a lesson and end the day with the same lesson (morning and night routine). * highly recommended* Baby sign language book Sign language book Book to teach baby sign language Book to teach baby sign language Book to teach toddler sign language LTKBaby LTKFamily LTKKids