In what I think was the first book, a boy (and maybe a girl?) control a space ship with their minds. They are in a vast room with bowl-like depressions in the ground that they stand in to control the ship. In another book a girl is in a coma in our world, but she is living her life in another reality also. There was also a part in one book where a kid disappeared while in a tunnel on a roller coaster.
That's all I can remember. Can anyone identify the series?