Place Value

This model illustrates the concept of “place value” using “decimal wheels”, represented as pulleys, and as quantities of balls. Balls are loaded from a reservoir by clicking on buttons labeled “+1”, “+10”, and “+100”. As the balls fall, they advance a paddle wheel which drives the “ones” pulley one unit which drives the “tens” pulley one tenth of a unit which drives the “hundreds” pulley one hundredth of a unit. After this, the balls fall into a tube labeled “ones”. When the tube is full of 10 balls, the tube of balls is moved into a box of tubes in a container labeled “tens” and when this box is full it is moved to a stack of boxes labeled “hundreds”. Counters track the total number of balls loaded, the current place value of each wheel, and the number of elements in each container. Clicking “new” in the upper left corner resets the page.