Förmodligen "Infinity Jinx" (2005) av Margaret Peterson Haddix, som samlades in Oväntat : 11 Mysterious Stories . Räcker omslaget en klocka?
Jag hittade den genom att söka den här sidan för [story-identification] learn read children som återvände Story ID: Pojke som fastar vid 5 år med robot barnflicka som matchar din beskrivning ganska bra.
En forskare introducerar ett vaccin för att stoppa barn från åldrande, så att föräldrar aldrig får drabbas av förlusten av att de ser upp och går hem.
Från frågan ovan:
The injection/serum used to halt the aging process was developed by a scientist, who when he first shared his findings had a 5 year old son and injected him, then told the onlookers/potential buyers/other parents to come back in 20(?) years. When they did, their children were adults and no longer needed them or were ungrateful layabouts, and the scientist's son was still 5 years old, cute, needy, etc.
och
When a child whose aging process has been stopped learns how to read, they begin aging normally again, so the parents don't want them to learn to read.
Huvudpersonen är en mamma som bor i ett lägenhetskomplex och gör nästan samma sak varje dag med sitt obelösa barn.
Kanske du misstog barnflickan för mamman? Från översynen kopplad i det tidigare svaret:
When mommy and daddy are at work, the robot-nanny is there to care for him by cooking, cleaning and guarding the door when the doorbell rings until the person leaves.
Ett upproriskt barn i komplexet introducerar detta barn till böcker.
Också från granskningen:
It’s a boy, taller than him and a face he hadn’t seen before. Curious he opens the door just a tiny bit and alarms burst into sound and the robot-nanny races over to close the door and place him back to the safe security of the couch. Only she didn't. The strange boy rushed in and to her back and she stopped moving. This is the start of Timmy’s adventure as he learns about learning, reading, writing, counting and many other things we find so commonplace and bring. He learns how to read the clock on the wall and basic books. He also learns he is hungry for more knowledge. Timmy wishes to grow.