This page explains how to use a protractor and contains an animated video showing how to draw an angle using a protractor and ruler.
Math Is Fun

AAA Math features a comprehensive set of interactive arithmetic lessons. Unlimited practice is available on each topic which allows thorough mastery of the concepts. A wide range of lessons (Kindergarten through Eighth grade level) enables learning or review to occur at each individual's current level.
Immediate feedback prevents practicing and learning incorrect methods, which is a common result of traditional homework and worksheets. Practice can continue as long as desired in a nonthreatening format which helps build selfesteem and confidence.
AAA math

A description and comparison of number names and place values
math n stuf (Math Spoken Here)

If you need to check your conversion, you can use this site. You enter your conversion and it will do it for you. Great way to check your answers.
General Units

Worksheet generator for practice reading a tape measure.
The Math Worksheet Site

I don't know how many deciliters in a hectoliter
Tutor.com

The page starts with an explanation of how the protractor works. The student is then given a series of 10 angles to measure with a virtual protractor. The site checks the students answer.
Math Playground

Measurementsconversions, length, area, volume, etc
Math Is Fun
