Jack watched over his kids and tried to give them hints, he made Jake think that he and Sam had painted the walls black and white when really he did. He also changed their clocks to be one hundred years in the future or make them think that 2015 was the past. Jake and Sam were so confused that they thought that they needed to find answers about what happened. They eventually went to the tree, got the sap, and then put the sap on the stick. Sam and Jake had made a time staff that could alter time in any way that they choose.
Sam and Jake made themselves different ages, they didn't know how to use the staff properly, yet. Sam and Jake eventually found an old painting in their attic and they used the staff and realized that the laughing face on the paint was their dad...