Glitch

From the critically acclaimed author of Float comes a new whirlwind adventure about a pair of kids who must break all the rules of time travel, perfect for fans of Gordon Korman and John David Anderson. Regan Fitz and Elliot Mason have been enemies since they started training to become Glitchers-people who travel through time to preserve important historical events. But everything changes when they find a letter from Regan's future self, warning them about an impending disaster that threatens them and everyone they know.
Will they be able to set aside their past in order to save the future? Enemies to Friends: Regan Fitz and Elliot Mason are total opposites and sworn rivals. But when a cryptic message arrives from the future, they're the only two who can decipher it. Time Travel Adventure: Join the Glitchers as they jump into the past to preserve crucial historical events, from the Lincoln assassination to the Boston Tea Party, all while trying to outsmart a threat to their own timeline.
Reluctant Partners: She has the gut instinct; he has the book smarts. To save their future, this bickering pair will have to learn to trust each other-and fast. A High-Stakes Mystery: Who sent the letter from the future, and what disaster are they trying to prevent? The clock is ticking for Regan and Elliot to solve the puzzle before it's too late.