Since around 18 months, DD loved puzzles. There was one where she had to make 3-letter and 4-letter words where each alphabet was a piece of the jigsaw and had a part of the picture. (I'll try to recall the toy's name). For instance - FOX is made of three pieces F-O-X and when put together also made a picture of a fox. Soon, DD was also able to pick one piece and could tell which animal or object's name that piece belonged to.
Also, around the same time, we had got a toddler-friendly wall map of United States and taught her the states. At 22 months she could identify about 15 states and enjoyed us calling out "Wyoming" and she doing a Hi-Five like action tapping over the state on the map.
