Sawan 221 Series of books is a treasure-trove of strange, unique and fascinating. Each and every explanation in 221 facts about Earth has been made in a very lucid language keeping in mind the age-group of children. The colourful illustration that goes with the explanation clarifies it all the more. 221 facts about Earth is surely useful to those, young and old alike, who have a scientific bent of mind and are on the look-out for something new and exciting.