THE DOUBLE-DECKER BUS: EARLY ADDITION AND SUBTRACTION (CONTEXTS FOR LEARNING MATHEMATICS, GRADE K-3: INVESTIGATING NUMBER SENSE, ADDITION, AND SUBTRACTION) By Maarten Dolk & Catherine Twomey Fosnot & Nina Liu.
THE DOUBLE-DECKER BUS: EARLY ADDITION AND SUBTRACTION (CONTEXTS FOR LEARNING MATHEMATICS, GRADE K-3: INVESTIGATING NUMBER SENSE, ADDITION, AND SUBTRACTION) By Maarten Dolk & Catherine Twomey Fosnot & Nina Liu.