@conference {761,
	title = {Designing a technology based learning environment for place value using artefact-centric Activity Theory. Research Forum Activity Theoretical approaches to mathematics classroom practices with the use of technology},
	booktitle = {Proceedings of the 37th Conference of the International Group for the Psychology of Mathematics Education},
	year = {2013},
	publisher = {Psychology of Mathematics Education (PME)},
	organization = {Psychology of Mathematics Education (PME)},
	address = {Kiel, Germany},
	author = {Kortenkamp, Ulrich and Ladel, Silke},
	editor = {Lindmeier, Anke M. and Heinze, Aiso}
}
