Linda Kase I purchased this for my 12 year old grandson, didn't realize it is a real "story book", and too childish for him. Fortunately his 8 year old sister is also into Polar Bears so she'll receive it, and probably love it, and he'll probably love it too, but would be insulted to get it directly.
Lillian I think this would be perfect for them. May I also recommend Cynthia Rylant's Cobblestone Cousins series. I think most girls that age would love them and they are usually around 50 pages. Hope that helps.