My 3.5 year old son loves this book - we are typically reading it at least twice a day. I love that there is a since of time involved, as each page covers a month in the year. Great for a preschooler who is just learning to get a grip on the calendar. The hermit crab forms symbiotic relationships with other sea creatures; another great lesson. Also super fun to read out load with lots of opportunities to "do" the different voices. There is a glossary in back - perhaps a little advanced for a 3 yr old, but I enjoyed that the first time I read through the book - it will be good when my son is a little older. I like that, although our hermit crab has to eventually leave his friends behind in search of a new home, he is able to pass along his old home to a younger crab. All this with the style of illustrations that we have all come to love in eric Carle books, makes this one a big winner!