I vividly remember reading this book in the fifth grade. I found it unscientific, wildly implausible, vague, and artistically undistinguished.
The book takes place at an unspecified date in the future when the sun is dying for an unspecified reason. The main characters--like many people on the planet--are leaving the earth--however, the nation that they belong to is poor, and cannot afford to take much with them. They can therefore only take a few crops and animals with them, and each person can only take a single book. The main character-- a young girl--chooses to take a green notebook with her, in which she records the events that take place on the new world. This, however, does not excuse the book's numerous scientific flaws, which for me made the book a laughable read.
*Stars, when they die, do not shrink and turn blue as the book depicts--they instead turn red, and even a sun-sized star would grow in size.
*Though the ship has a computer that is advanced enough to play games with the passengers, it never occurs to the designers to place a library of books in the computer. Additionally, it seems that the author never anticipated the cheapness of computing technology which would eventually arise.
*An interstellar journey would never take four years unless one had been using some currently unknown method of superluminal travel. The book makes no mention of this.
*The planet is too Earthlike--one cannot expect that there would be anything resembling a tree, a blade of grass, or other feature of terrestrial biology on that planet.
*Life cannot become crystalline either from living in a soil or from a diet. This is simply, utterly absurd--such a thing is effectively equivalent to completely restructuting the elementary composition and molecular processes of an organism without killing it--and the simplest way by which one could legitimately explain this concept in a serious work would require the use of extremely advanced nanotechnology.
The scientific errors are potentially ignorable, but, as I am very knowledgeable as to science, I found that these books--as well as the poor presentation of the story by my fifth grade teachers--were not at all of any interest to me.* The writing style is only barely distinguished with respect to other authors, and it is funny that a child would even be able to use the word "treacle", as the main character does in the first chapter.
*Footnote: I have a grudge against the school, in part for how they taught this book. For example, when we as a class arrived at the scene where the children discover a sweet substance, the whole class did a science essay on sugar, never once mentioning that not all sweet substances are sugars. It was only a fifth-grade class, of course--but I was highly annoyed even then, especially when a kid told me that "sugar was made of carbon dioxide"--a conclusion made from our experiments with using yeast to measure sugar. I could go on to discuss the other crap they taught us, but I will discuss that in a different review.