With infants, Comment on what they’re doing or looking at: Hang a soft toy, a photo, or other interesting object near your changing area. When your baby notices it, name the object/person and describe it (that's your fuzzy bear, it's brown and so cuddly). This can be a great conversation starter during clothing changes.
With toddlers, Imitate them, and add words: Toddlers love to ask adults “What’s that?” and “Why?” When you respond, be sure to add new words to expand on what they know, “This is your short sleeve shirt with a dinosaur on it.” and “It's winter right now so we need to find a long sleeve shirt so you are warm.” Listen to their response and continue the conversation by giving more information or asking them questions.