@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 },
}