Master addition and subtraction with carrying and borrowing for first graders. This is a Benesse Challenge 1st Grade educational tool. It explains addition and subtraction with carrying and borrowing in an easy-to-understand way for children who don't understand these concepts. It also includes a small game. It's an old item, but the batteries still work, so I will send it as is. As a bonus, I will also include the Challenge 6th Grade English and History Mobile Master. This is an unused item, but it does not include the earphones. Please note that it also requires batteries. Both have been tested and confirmed to be working. #Benesse #Challenge1stGrade #Challenge6thGrade #AdditionWithCarryingMaster #SubtractionWithBorrowingMaster #EnglishMaster #HistoryMaster #ChallengeEducationalMaterials #KodomoChallenge