Use pictures from your ward library of people - children and adults, being baptized and/or confirmed. Ask a child to pick a picture and tell something about baptism. If they have been baptized, they could tell one thing that they remember about it. If they haven't, they could tell something that they are looking forward to being baptized.
Sing one of the baptism songs then ask another child to share their thoughts. continue singing a song after each child. You might want to ask one of the adults to share also.