Time Benders — Gary Paulsen

Super-brain Zack Griffin and hoops fan Jeff Brown wouldn't normally hang together. But when both boys win trips to a famous science laboratory, they find out they do have one thing in common: curiosity. They discover that one of the machines in the lab can "bend" time--and Jeff and Zack end up in 1334 B.C. Egypt! There's a plot afoot to kill King Tutankhamen, and the Time Benders have to decide if they should they save the Pharaoh or just leave well enough alone.