Young John Muir had two great passions: walking in the woods and tinkering with mechanical things. As a teen he constructed a peculiar alarm clock that shook the leg of his bed to wake him up, and later, as a student at the University of Wisconsin in the 1860s, he created a desk-clock that held a book open for half and hour and then closed it, moved it aside, and replaced it with the next book Muir needed to study. (See a photo here.)
Muir won prizes for his mechanical wonders and might have pursued a career in engineering if he hadn't suffered an eye injury that hampered his tinkering and sent him on a trek that would consume the rest of his long life: walking in the woods (and fields and mountains and glaciers) all across the North American continent.
Muir walked from Indiana to Florida, took a boat to California, and walked all over the west to pursue his passion for wilderness--all without the benefit of cell phones or GPS or modern hiking gear. The titles of his books map his journeys: A Thousand-Mile Walk to the Gulf, My First Summer in the Sierra, The Mountains of California, Our National Parks, and more. Today he is remembered as the guiding force behind the formation of our national parks and the father of the Sierra Club.
What would happen to Muir if he were a teenager today? A fidgety boy with a foreign name (Muir was an immigrant born in Scotland!) shows up at school carrying an odd contraption he has created and no one can figure out what it is--he'd be arrested, of course, just like Ahmed Mohamed, who took a homemade clock to school in Texas and was hauled off in handcuffs for constructing device that looked threatening (read it here).
The charges have now been dropped and young Ahmed is coping with his fifteen minutes of fame. Muir, on the other hand, didn't make his name until he'd walked those thousand miles, hopped that boat, and written those books. But his life would have taken an entirely different path if he hadn't had the freedom to pursue his passions.
Let the kids tinker; let them walk in the woods. You never know where they might end up or what kinds of wonders they'll discover or who, in the end, might be inspired to follow.