Fraction Comparison
Watched this video about Dor Abrahamson, http://youtu.be/qZaZGL-vP5E, and he had a non-computational tool for students to construct some understanding about fractions. Thought I'd make a more accessible GeoGebra version and this is it.
Drag either the red circle or the blue circle to change the length of the bars. The sketch will tell you when you match the fraction set by the sliders.
See also http://www.geogebratube.org/material/show/id/21709 for a different approach to fraction estimation.