"After eleven-year-old David Bravo wishes for a do-over of a disastrous day of middle school, he and a shapeshifting spirit guide try to right a wrong in his past"--

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?--Amazon.com

When thirteen-year-olds Jonah and Chip, who are both adopted, learn they were discovered on a plane that appeared out of nowhere, full of babies with no adults on board, they realize that they have uncovered a mystery involving time travel and two opposing forces, each trying to repair the fabric of time.

Jack and Annie travel to Vienna, Austria, in 1762 where they meet the young Wolfgang Amadeus Mozart and his sister and help save the budding genius' life.

The magic tree house whisks Jack and Annie to India during the Mogul Empire in the 1600s to search for an emerald needed to break a magic spell.

After thirteen-year-old Tucker Feye's parents disappear, he suspects that the strange disks of shimmering air that he keeps seeing are somehow involved, and when he steps inside of one he is whisked on a time-twisting journey trailed by a shadowy sect of priests and haunted by ghostlike figures.

"The time has come for Cleo to fulfill the ancient prophecy that declares her a savior and a hero, a prophecy she still struggles to accept. Cleo is joined by old and new friends as they fight to defend the galaxy she's come to call home against the evil Xaius Octavian. The Queen of the Nile must summon the strength to face down her enemy one last time, and keep both her friends - and herself - alive."-- cover page 4.

My name is Hannah Dory and I need you to believe me. NOW: Hannah is brought to Belman Psych, told she is suffering from hallucinations and delusions. Hannah knows the truth: she must return to the past and save her sister. Could Jordan, the abnormal psych student who seems to truly care, be the answer she's looking for? 1347: Hannah and her village are starving to death in a brutal winter. Hannah seeks out food and salvation in the baron's castle....

Since learning she is the Ruby, the final member of the time-traveling Circle of Twelve, nothing has gone right for Gwen and she holds suspicions about both Count Saint-German and Gideon, but as she uncovers the Circle's secrets she finally learns her own destiny.

With the realm at peace and few dragons about, the Knights of the Round Table are bored, so Merlin sends them to face the most terrible lizards of all--dinosaurs.