Rebecca decided to see how the slim and attractive Jake changed as he aged - Jake was tall, svelte and thin - he was known as a bit of a literature nerd, but despite that he defied the stereotype by being attractive if not in the same way as the jocks, and outgoing. Jake for his part hardly even noticed the intense look coming from the teacher, or the strange energy that imperceptibly radiated off of her for a moment. Indeed, Jake was mostly invested in the reading material for the class, trying to pay attention to the exact subtext and possible questions to come on the next test.
Jake adjusted himself in his seat as his glutes and legs were the first things to change in his loose jeans, the cheeks of his ass bulging with muscle as he aged, his quads and hamstrings thickening and growing as they asserted themselves against his jeans, which were starting to get a deal tighter. That ass was at first just the well muscled derriere of a fitness model, made for aesthetic appreciation.
Jake tried to keep reading as he rolled his shoulders, his back and shoulders strengthening as his back widened and waist narrowed. His lats surged into form, and pushed his arms out a bit more, his shoulders keeping pace nicely by becoming broad boulders of muscular size and incredible tone. Each striation pushing out against his loose shirt. Jake grunted and shook his arms, keeping his attention on the pages...
...Which was just as good because his arms were the next thing to change as he made his way into his twenties. Dark hair grew in on his arms, which did not do much to obscure the incredible size and tone growing in - his biceps hitting eighteen or nineteen inches adeptly quickly, triceps forming into the telltale horseshoe form, his biceps almost looking like he had a softball or more stuffed in his arm. Even his forearms muscled up well, swelling as a result of forearm curls done in the gym.
Lastly, he adjusted his shirt as his pecs pushed out more and more, growing to a great and sizable force in the fore. His body was toned and excellently muscled, which only made his thick, strong abdominals and obliques more astonishing. Rebecca could almost not keep her eyes off of her aging subject.
The svelte and handsome face of Jake was the next to change, bombarded by testosterone. Jake's face became devastatingly masculine and handsome as he aged, thick jawed and strong featured. Rebecca was almost starting to wonder if it'd really be Jake in there after all was said and done. Jake for his part grimaced as he felt his face change, but still did not notice. His thick hair grew into a fashionable and well done short cut, slight stubble showing on his face...
Jake stirred in his seat and tugged at his pants as the next phase of the change occurred. Getting well into his thirties, Jake felt his manhood thicken and grow, years of testosterone and work making him quite sizable in the sack. He scratched at the seat of his pants, feeling his balls swell and grow. It seemed if anything it was his thirties when he took his fitness from mere fitness model to outright buffed out bodybuilder;
His body swelled with size, almost uncannily, and Rebecca suppressed a pleased noise as she watched his pecs and shoulders first swell, followed by everything else. He was growing, aging, growing...he looked so uncomfortable suddenly, trying to keep himself from reacting to all of this. He just wanted to focus on the reading, dammit! Jake gulped when he felt his cock engorge in his pants, deciding he'd need to take some time after class to get that back to normal before he had to embarrass himself in PE.
So he thought anyway as he proceeded through his thirties and well into his forties. By the thirties his face was aging, but it was in his forties when his wrinkles and crows feet truly came in. But even so, as his hairline retreated a bit, Rebecca still saw a handsome stud, just somewhat more mature than most. She kept her eyes on him as he looked around, blushing at the people with their eyes on him. His chin and jawline stayed strong even as the stubble thickened and then got buzzed off.
His changes halted at 44, and thankfully class ended before long. Rebecca decided to see about this and whether Jake was still...well, Jake. "Jake, do you think you could talk to me after class?"
Jake gulped, wincing visibly, he wondered if she noticed his ill-fitting clothes - he'd need to get some new ones stat! - and hopefully he hadn't been too caught up in the reading. "Uhh yeah, Ms. Clarkson? What's this about?" Holy shit, Jake thought, is that my voice? What's wrong with it?
Rebecca had not perceived it at the start but damn if she didn't see it now. Jake was now like six foot four inches tall, and she was very okay with how tall, dark and handsome Jake had turned out.