BBC
Bbc: Angles
You can pick up some valuable pointers on angles and lines here. When you finish working your way through the pages you can take an on-line "Test Bite," and check your understanding.
ClassFlow
Class Flow: Angle Measurement
[Free Registration/Login Required] This flipchart uses the protractor tool to understand the classification and naming of angles: acute, obtuse and right.
Other
Online Conversion
Conversion calculators galore! Convert just about anything from one measureable unit into another measureable unit here with over two dozen calculators. Each of the links is specific to a measureable quantity. Some examples include...