Free only in November. This is a virtual manipulative to support developing number sence and arithmetic concepts. Watch a video of the app: http://www.youtube.com/watch?v=9bPtA8lkXt4 Two (sub-)quantities together result in a new total quantity. This is called addition. And if you take away a subquantity, another subquantity remains. This is called subtraction. With this virtual manipulative kids kann explore and learn the relationsships between subsets and total sets. This is how it works: Touch the screen with your fingers to produce token. You can also move these tokens with your fingers. Move the tokens out to the top to delete it. Tap on a number to sort the token. Spipe over a number to hide it or to show it again. Pull down the shutters to hide one half of the tablet. Shake the tablet to empty it. The basic operations addition and subtraction are based on the concept that a quantity can be split into subsets and you can join the subsets again (part-whole concept). If kids understood the relationsship beetween partial and total quantities, an essential cornerstone has been laid for successful mathematical learning. This virtual manipulative is an tool to explore and experience these concept. This app does not include tasks. For successfull and effective learning kids use this app to solve tasks that callange them to experiment and reflect. Here are some examples: How can I quickly produce 8 token with my fingers? How do I have to sort the tokens to see the number without counting? On one side there are 4 token, on the other side 3 token. How many token are this in total? What happens, if I move 1 (2, 3, ...) token from one side to the other? What happens, if I remove 1 (2, 3, ...) token from the tablet? How many configurations are possible to split 10 token on the two sides? On one Side of the tablet are 3 token. How many token do I have to put on the other side to have 7 token in total? On the tablet are 10 token. You can only see a part of it. How many token are hidden? I put 8 token on one side of the tablet. Then I take 5 token to the other side. How many token are left?