@conference {764,
	title = {Development of a Flexible Understanding of Place Value},
	year = {2014},
	publisher = {A Mathematics Education Perspective on early Mathematics Learning between the Poles of Instruction and Construction (POEM)},
	organization = {A Mathematics Education Perspective on early Mathematics Learning between the Poles of Instruction and Construction (POEM)},
	address = {Malm{\"o}, Schweden},
	url = {http://www.mah.se/upload/FAKULTETER/LS/LS-seminarier/POEM/Ladel_Kortenkamp\%20-\%20Development\%20of\%20a\%20flexible\%20understanding\%20of\%20place\%20value.pdf},
	author = {Ladel, Silke and Kortenkamp, Ulrich}
}
@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}
}
