@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 },

pages = { 224-242 },

}