Only ten minutes had gone by since the last rest stop, but to me it felt like an hour. My knee bounced. My leg jiggled. My fingers drummed out syncopated rhythms on the door handle. “Jennifer,” said my older sister, Ula. “Stop tapping.” I gritted my teeth and began slapping the side of my thigh instead. “It’s Jenny.” “Jennifer, you’re still making noise.” “My name is Jenny!” “Ula, Jenny, stop bickering,” said Mom in that stiff, controlled voice that meant she was trying very, very hard not to yell. “Especially you, Ula. You’re 15. You should know better.” Dad turned around in the passenger seat. “Girls, you’re stressing her out. Why don’t you play Twenty Questions?” “Yes,” I said instantly. Ula groaned, but I noticed the look of satisfaction in her brown eyes. “I’ll start,” she said in a practiced drawl. “Fine.” The car fell silent while Ula thought of her object. I stared out the window at the wall of leafy green trees parading down the side of the road, bars of Mozart and Seitz and Boccherini running through my head. My own face—straight, thick black hair framing yellow-hazel eyes—looked dispassionately back at me. After a while, I switched to thinking about strange things that could happen as a result of insufficient AI attempts: A self-driving car is driving down a road. A tree falls across the road, and the car drives into it and explodes. However, right before it explodes, the car sends a record of what has happened to all the other self-driving cars. Instead of concluding that you should stop if a tree falls across the road, the cars all conclude that you should not drive near trees. I smiled at the image of cars inexplicably avoiding large swathes of forest. “All right,” Ula announced. “I’m ready.” Finally, I thought, turning from the window. My sister’s eyes were narrowed, as if in challenge. Her curly blonde hair had frizzed up around her face, making her look like some sort of evil villain in a comic book. “Is it a vegetable?” “No.” Ugh. Already I just felt like lying down and going to sleep. “Is it an animal?” She hesitated. “No.” The word seemed drawn-out, uncertain. That caught my attention. Ula was never unsure of something in Twenty Questions—or any game, for that matter. At least, she never showed it. “Is it a mineral?” I almost asked, but caught myself. Since there were only three categories—vegetable, animal, or mineral—it had to be. Furious at my mistake, I took a deep breath and said, “Is it bigger than a bread box?” “No.” “Is it a sort of big rock?” “A small boulder. No.” “Is it a regular object?” “No.” “Can it be seen if I look outside?” “No.” I hated how calm she was, how robotic, how unfazed by my questions. If this were a battle, I thought, she’d be winning. “Have we seen it before?” “Yes.” I blurted out the first question that came to my mouth. “When was the last time we saw it?” Ula’s mouth curled into a mocking sneer. “That’s not a yes-or-no question.” I gritted my teeth. “And it counts.” “Was the last time we saw it more than one year ago?” “Yes.” “More than two?” “Yes.” “More than three?” “Yes.” “More than four?” “No.” So when I was seven. Okay, this was not fair. But I knew I couldn’t back down now. I cast my memory back to important things that had happened four years ago. That was the year Dad had hurt his foot, leaving him unable to drive and with a limp. And the thing he had dropped on his foot was . . . Oh. The Christmas tree. Which would be classified in the vegetable category. I searched for other things, and my mind was drawn to a sweltering July day in Washington, D.C. Ula and I had had identical dripping raspberry gelato cones, which we licked desperately as we wandered with our parents around Capitol Hill. Despite my efforts, my hands and face had been glazed with bright red liquid. We had walked through Eastern Market, and even though I saw the same thing every day, I had been mesmerized by all the crazy kinds of produce for sale. The gelato on my face and hands somewhat mopped up, I had gingerly felt the scales of an artichoke, nervously prodded a pineapple’s serrated leaves, and generously tasted every plate of fruit samples, stopping only when my parents (and Ula) had dragged me away with angry scolding. Then, at Ula’s and my plaintive requests, we had gone to the library, with its blissfully cool aisles of bookshelves and its little reading tables by the windows. I had plopped down at one of them with a foot-high stack of Magic Tree House books I knew I wouldn’t be able to finish while Ula prowled the shelves. “ Something about that blissful day, so full of possibilities, so free of obligations, felt important. But nothing about it had anything to do with minerals. We had left the library and continued down the sweltering street. Ula and I had run back and forth along the red-bricked sidewalk, gathering up handfuls of fallen flowers from the crape myrtles and presenting them—I more proudly than Ula—to our parents. Secretly, I had swiped several sprigs of mint from a thick clump growing in someone’s front yard and peeking through the black-painted fence, thinking to use it for tea later. Something about that blissful day, so full of possibilities, so free of obligations, felt important. But nothing about it had anything to do with minerals. Reluctantly, I shifted the focus of my mental metal detector. Soon, it felt as if I had gone through every memory I had of the year 2014. There was my birthday in August—a water fight at Lincoln Park, with high-velocity squirt guns and hundreds of water balloons. And Ula’s in March, spent holed up inside our not-exactly-gigantic apartment with