Frankie Muniz isn’t the only genius kid on ”Malcolm in the Middle”: An episode that will air during February sweeps was conceived by — prepare to hate yourself, aspiring Hollywood scribes — an elementary school student. Last fall, Alexandra Kaczenski, the 11-year-old niece of ”Malcolm” costume designer Heidi Kaczenski, brainstormed an episode in which Jane Kaczmarek’s Lois fantasizes about life raising daughters instead of sons and presented a two-page outline to series creator Linwood Boomer. ”I thought, Sure, I’ll take two seconds of my time,” he recalls. ”So I read through the thing, I ran up to the writers’ room, and I said, ‘Okay, I was just pitched an idea by Alex Kaczenski…you know that little girl that hangs around with Heidi?’ And they went, ‘Okay, tell us.’ And I [did] and the whole room just stopped and went, ‘That’s a really good idea!’ and I was like, ‘I know!”’ Boomer then asked Kaczenski, now 12, to pen a longer outline — which he bought. Since then, he’s encouraged her to offer up more story concepts. So, does Kaczenski have any other bright ideas? ”Yeah,” she notes nonchalantly, ”but I’m not telling them yet.” Guess we’ll just have to wait until May sweeps.