Percent Change Calculator
- Measures the difference in values using percentages. Includes bar graphs with the answer.
- http://www.percent-change.com/

Learning About Time
- History and description of clocks with lessons on telling the time. Includes an interactive tutor. [Requires Java]
- http://arcytech.org/java/clock/

The Modern Metric System
- Dictionary of metric units explaining the principles and history of the system.
- http://web8.ehost-services.com/cdkaese/metre/

Metric Conversion Chart
- Online metric conversion calculator includes metric, US customary and Imperial unit conversions.
- http://www.sciencemadesimple.com/conversions.html

Online Units Conversion
- Gives equal values for areas, volumes, circle measurements, computer storage, currencies, distance and length, energy, fuel consumption, power, pressure, speed, temperature, time, torque, and weights.
- http://convertplus.com/

GCSE Maths: Measurement
- Includes length, area and volume and the use of prefixes in units. With worked examples and animations.
- http://www.gcse.com/maths/measurement.htm

Conversion Calculator
- A simple calculator to convert between various units.
- http://www.thehaws.org/convert.shtml

Apples4theteacher.com
- Measure the teddy bears game.
- http://www.apples4theteacher.com/measure.html

Metric Measures
- Offers equivalents for common measurements, plus how metric units are used in sports and the kitchen.
- http://www.nist.gov/public_affairs/kids/metric.htm

The Ruler Game
- Timed game will test how quick you can read a ruler.
- http://www.rickyspears.com/rulergame/

Origins of Measurements
- Compares units of ancient times with modern ones.
- http://www.iofm.net/community/kidscorner/maths/origin.htm

Measuring Angle and Distance with your Thumb
- How to use body parts to estimate measurements.
- http://www.vendian.org/mncharity/dir3/bodyruler_angle/

Jack's Math
- Provides several methods for determining length, width and height.
- http://www.nps.gov/whmi/educate/ortrtg/11or1.htm

How To Read A Ruler
- Article describes all of those little lines and markings.
- http://www.woodzone.com/articles/Read_A_Ruler.htm

Funbrain.com
- Measurement game - Game which has several levels of difficulty for both English and metric rulers.
- http://www.funbrain.com/measure/

FAQ: How do I read a ruler?
- Instructions on how to use metric and English rulers.
- http://www.onlineconversion.com/faq_05.htm

Unit Conversions
- Online conversions from physics units to other physics units. Includes a comprehensive set of units with definitions.
- http://www.chemie.de/tools/units.php3?language=e

Temperature Converter Fahrenheit Celsius (Centigrade)
- A temperature converter for Celsius and Fahrenheit.
- http://www.albireo.ch/temperatureconverter/

Metric Conversion Tables
- Conversion factors and online calculators for metric and imperial units.
- http://www.metric-conversion-tables.com/

Metric 4 US
- A site promoting the metric system which argues why metric is better and English is worse. Provides an English-metric online calculator.
- http://www.metric4us.com/

How Many?
- A dictionary of units of measurement: explanations of the metric system, System Internationale (SI), English customary system, and other modern measuring systems. Plus extensive links to other measurement-related Internet resources.
- http://www.unc.edu/~rowlett/units/index.html

A Dictionary of Units
- A summary of most of the units of measurement to be found in use around the world today (and a few of historical interest), together with the appropriate conversion factors needed to change them into a standard unit.
- http://www.ex.ac.uk/cimt/dictunit/dictunit.htm

Metric Conversion
- Java metric conversion calculator for length, weight, pressure, and volume.
- http://www.worldwidemetric.com/metcal.htm

Measurement Worksheets
- Features printable worksheets. Includes English and Metric System pages.
- http://www.edhelper.com/measurement.htm

CyberSleuth: Units of Measurements Worksheets
- Twenty-three printable worksheets for elementary school-aged children. Focuses primarily on conversion of units of length.
- http://cybersleuth-kids.com/sleuth/Math/Math_Worksheets/Units_of_Measurement/

Convert-me.Com
- Interactive calculators for many common and exotic measurement systems, including metric, Ancient Greek, Roman, and old Russian.
- http://www.convert-me.com/en/