This is one of two Science Fictions stories that had excerpts in our readers for school that I still remember. In this one, a kid wakes up and everything is slightly different. By the end of the excerpt, he figures out that he and his family are in a cage at a zoo whose owners have (assumedly incorrectly) identified humans as going extinct. The boy stages an escape, and figures out that the ant-like aliens running the zoo are blind to movement.
I've always wondered what happened in the rest of the story.