The final for a high school Survival Class is for the class to survive on another planet for 2-10 days with only what they can carry on their person. Unfortunately, the gate between earth and the planet is broken, leaving the students to fend for themselves for 2 years. They create their own city with its own government and marriages.
I found this book to be quite an interesting read. Heinlein definitely included his military survival training knowledge in the situations the students encountered on their new host planet. It certainly makes it more interesting that it's more realistic.