One of my favorite books from our latest library visit is Once Upon a Time, Upon a Nest by Jonathan Emmett, illustrated by Rebecca Harry. I love this book!
The story is about a little duckling that is behind its siblings in everything right from the start. Her daddy worries about it and wonders if she'll ever catch up. But her mommy keeps saying, "She will, in her own time." And sure enough she does.
I love the message of the book! Each child will develop in their own time. Don't get caught up in comparing them and expecting them all to develop at the same speed. Relax and let them develop at their own speed.