Except for the aliens, it sounds very much like you're describing <PERSON> "Profession", in which children are taught to read by imprinting at 8 years old on "Reading Day", and are assigned a profession (and imprinted with full professional expertise) at 18 on "Education Day".
Of course, Reading Day had been different. Partly, there was the simple fact of childhood. A boy of eight takes many extraordinary things in stride. One day you can’t read and the next day you can. That’s just the way things are. Like the sun shining.
[. . .]
Then the helmet was taken off his head, and the light was so bright that it hurt his eyes while the doctor’s voice drummed at his ears.
The doctor said, “Here’s your card, <PERSON>. What does it say?”
George looked at his card again and gave out a strangled shout. The marks weren’t just marks at all. They made up words. They were words just as clearly as though something were whispering them in his ears. He could hear them being whispered as he looked at them.
[. . .]
<PERSON> shrugged. “I’m sure you know how Earth runs its Educational program, <PERSON>. Practically any human being can absorb practically any body of knowledge, but each individual brain pattern is better suited to receiving some types of knowledge than others. We try to match mind to knowledge as well as we can within the limits of the quota requirements for each profession.”
<PERSON> nodded. “Yes, I know.”
“Every once in a while, <PERSON>, we come up against a young man whose mind is not suited to receiving a superimposed knowledge of any sort.”
“You mean I can’t be Educated?”
“That is what I mean.”
“But that’s crazy. I’m intelligent. I can understand –- He looked helplessly about as though trying to find some way of proving that he had a functioning brain.
“Don’t misunderstand me, please,” said <PERSON> gravely. “You’re intelligent. 417
There’s no question about that. You’re even above average in intelligence. Unfortunately that has nothing to do with whether the mind ought to be allowed to accept superimposed knowledge or not. In fact, it is almost always the intelligent person who comes here.”
[. . .]
“Can’t you try Educating me? You haven’t even tried. I’m willing to take the risk.”
“The law forbids us to do that, <PERSON>. But look, it will not be bad. We will explain matters to your family so they will not be hurt. At the place to which you’ll be taken, you’ll be allowed privileges. We’ll get you books and you can learn what you will.”
“Dab knowledge in by hand,” said <PERSON> bitterly. “Shred by shred. Then, when I die I’ll know enough to be a Registered Junior Office Boy, Paper-Clip Division.”
[. . .]
“Well, anyway, it was all clear to me, as though I had known it all the time but wouldn’t listen to myself. I thought: What was it I had wanted Novia to let me do? I had wanted to go to Novia and take a batch of un-Educated youngsters and teach them out of books. I had wanted to establish a House for the Feeble-rninded – like here – and Earth already has them – many of them.”
Omani’s white teeth gleamed as he smiled. “The Institute of Higher Studies is the correct name for places like this.”
“Now I see it,” said <PERSON>, “so easily I am amazed at my blindness before. After all, who invents the new instrument models that require new-model technicians? Who invented the <PERSON> spectrographs, for instance? A man called <PERSON>, I suppose, but he couldn’t have been tape-Educated or how could he have made the advance?”
“Exactly.”
[. . .]
“You can’t be told. That’s exactly it. It’s the final test. 417