University of Texas at Austin
Mathematics Teks Toolkit: Buttons, Buttons, Everywhere!
Students use buttons to explore shapes, color, size and sort them into groups.
Shodor Education Foundation
Shodor Interactivate: Bar Graph Sorter
An applet allows students to sort shapes into a bar graph by color and shape. The learning resource consists of the activity, instructions, instructor notes, and additional resources.
The Franklin Institute
The Franklin Institute: Classified
At this site from The Franklin Institute you can practice classifying objects according to physical structure and characteristics.