There's this great sketch by dhabecker, Arrange fractions, decimals, and percents, [url]http://www.geogebratube.org/material/show/id/15308[/url] that was helping my students.
He figured out a clever way to generate 4 rational numbers, to sort them by dragging, and to check if they were in the right order.
I've just added colors, a button for new numbers, and a way to check other than all right or not. (Inspired by the great game Mastermind.)
