To encourage our ducklings to start breaking out, we have moved one of Mrs. Higginbotham's ducklings into our incubator. I don't want the kids to think that one of ours has hatched. We will only keep it in the incubator for a short time, then move it back to her room. Once ducklings hear other ducklings, they are motivated to start piping (the scientific word for breaking the shell).
Keep your fingers and toes crossed that at least one will hatch!