Although I am not a rabid fan of Mr. Heinlein, considered by many to be the grandmaster of science fiction, I do believe that Tunnel in the Sky is one of his better efforts.
The book, which apparently was originally slated for the juvenile market, tells the story of Rod Walker, a bright young man on the verge of graduating from a futuristic high school. In the book's future, the Earth is a vastly overcrowded planet, and teleportation has supplanted the internal combustion engine and its (hell)spawn as a form of mass transportation, especially over great distances. In the book, teleportation also presents a solution to Earth's bloated population: all the excess people were 'teleported' to new worlds surrounding distant stars, and as such they became de facto colonists.
It turns out that the young Mr. Walker aspires to be an explorer of these new worlds, or at least involved in some way with their governance and/or exploration. As one of these 'Space-Age' pioneers, he could participate in establishing a beach-head for humanity in some far-flung area of the universe, scout the terrain to get the lay of the land, and give the all-clear for human habitation and colonization. Under this system, he could even a group of colonists to a new world.
However, in order to do this, Rod must first pass a survivalist's exam. Before embarking on his challenge, to which his parents vehemently object, he gets more than a little helpful advice and a few useful life skills from his older sister, a futuristic sort of Amazonian warrior, and a schoolteacher named the 'Deacon' (an apt title for he preaches quite a lot) who thinks fondly of Rod, calling him 'a hopeless romantic born into an age of practical men'.
I think Heinlein wrote this yarn as an extended lesson on good citizenship for minors. I especially liked the insights the 'Deacon' had on the human animal, and the advice that Rod's sister gave him with regard to the choice of a knife over a nuclear-powered Ray Gun in the bush. Awesome weapon power often breeds over-confidence, and can become a substitute for using one's brain, and powerful weaponry is absolutely useless against a thinking and determined adversary (certain dunderheads running strategic operations vital to our nation's well-being should take note of that particular lesson!).
In the end, the exploration bug gets into Rod's blood, and his fate is sealed. Unlike more than a few Heinlein novels, which tend to be preachy and over-bearing, this little gem passed on some very useful insights and life lessons. It would have been nice if Heinlein had written an encore, so that we could catch up with Rod in the future, to see what kind of man he had become as a result of his fateful choice.