Shodor VennDiagram Shape Sorter: Students choose a rule and sort shapes to fit the attributes.
Geoboard, by The Math Learning Center App- Using the GeoBoard app on the iPad, students create 2D shapes with given attributes.
Is This Shape a... Game emphasizes that there are many different shapes that are quadrilaterals
Pattern Blocks - Online Manipulatives - Students can use online manipulatives to create new shapes by combining them.
Illuminations Shape Tool - Students can virtually explore and manipulate shapes, they can cut and separate shapes to create new shapes.