@Article{ MOLINA_MASON:224-242,

author = { MARTA MOLINA and JOHN H. MASON } ,

title = { JUSTIFICATIONS-ON-DEMAND AS A DEVICE TO PROMOTE SHIFTS OF ATTENTION ASSOCIATED WITH RELATIONAL THINKING IN ELEMENTARY ARITHMETIC },

journal = { CANADIAN JOURNAL OF SCIENCE, MATHEMATICS AND TECHNOLOGY EDUCATION },

year = { 2009 },

issn = { 1492-6156 },

pages = { 224-242 },

}