Partition whole numbers and decimals into 100s, 10s, 1s, tenths, etc. Students are asked to do this in more than one way.
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With this Java manipulative, you can represent place value and exchanges in base 2, base 5, or base 10.
A Java implementation of Cuisinaire Rods. Very nicely done.
A Java implementation of Base 10 Blocks. Very nicely done.