Place Value Chart vs Calculation Triangle

Experience grouping and ungrouping in our decimal number system with this interactive place value chart. Touch the chart to create tokens and move them around with your finger. Is this always possible? Remove tokens by moving them to the top of the chart. Shake your iPad or iPhone to remove all of them. Some activities supported by this place value chart: - How can you create large numbers using the least number of tokens? - How can you remove tokens quickly without shaking the device? - What happens if a token is moved from the hundreds to the ones? And what happens if you first move it to the tens place and then to the ones? This brand new version features new options to show totals, both as a number and in written english. Furthermore it is possible to use it for decimal fractions. The educational design of this interactive place value chart has been developed by Prof. Ulrich Kortenkamp (Didactics of Mathematics, University of Potsdam, Germany) and Prof. Silke Ladel (Didactics of Primary Education, Mathematics, Saarland University, Germany). It supports the development of mental concepts for place values in decimal systems and targets elementary and primary and lower secondary education.

This virtual manipulative encourage the development of flexible arithmetic thinking. Watch a video of the app: http://www.youtube.com/watch?v=iN3b20F6UC8 A calculation triangle is splited into three fields. Each field can contain tokens. On each edge the sum of the two corresponding fields is written. And this is how it works: Touch with you fingers on a field to produce tokens and move them from one field to another. Move tokens out of the triangle to delete them. Close the shutter to hide a field. If you swipe over a number you can hide it or show it again. Shake the calculation triangle to emty it. This virtual manipulative does not include tasks. But you can use this app to create puzzle problems for a learning partner or to model and solve existing tasks. Here are some exemples for good tasks to effectively work with this app: Find the missing numbers? Figure out how many tokens are on the hidden field? How do the numbers change, if you ... ... add/remove one (two, three, ...) token to each field? ... move one (two, three, ...) token from one field to another? ... add one token to two of the three fields? ... Is it possible to have three odd numbers? Why (not)? Is there a relationship between the sum of the numbers and the total quanitiy of tokens on the fields? Is it possible to produce any numbers or are there restrictions?