This is a YA.
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PNH is talented at shifting the gold from the dross: his collections are always better than the generally crap anthologies usually produced.
A personal favorite is Terry Bisson's "They're Made Out of Meat," in which aliens about to make First Contact with us are horrified by what they find. Sci fi short stories are much more likely to have a surprise one-two punch at the end, one that warps assumptions made during the story. This anthology has some great ones: Spider Robinson's "Serpents' Teeth," Debra Doyle and James D. MacDonald's "Uncle Joshua and the Grooglemen," and Robert Charles Wilson's "The Great Goodbye." Two other standouts are David Langford's "Different Kinds of Darkness" (I just love this type of school story, which for some reason reminded me of that story where there's only one day every 7 years where you can go outside on Mars, and one little girl is really excited about it but the other kids lock her in a closet so she misses it. It's actually a really dark children's story that always made me angry but thirteen years later, I still remember it.) and Greg van Eekhout's "Will You Be an Astronaut?" which reads like a very creepy children's story. I should mention that Jane Yolen's "Cards of Grief" is a pointless meander of a story that is clearly *supposed* to have a shocking ending but is instead very obvious, Kim Stanley Robinson's "Arthur Sternbach Brings the Curveball to Mars" is a boring sports story with no point at all, and Orson Scott Card's "Salvage" is a story about Mormons post-apocalypse, and though narrated by a non-Mormon it made me uncomfortable.
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