The Math Manipulatives portion of the Math Playground site offers some great Math tools. You will find Fraction Scales, Fraction Bars, Decimal Scales, Probability Spinners, Pattern Blocks and many others. The tools allow you to manipulate and add your own information to solve or explore a problem.
Fraction Bars (pictured above) allows you to set the numerator and denominator for each row by sliding to a different value. The number titles can be turned on or off.
No registration is required to use the site which makes it easy for teachers and students to use. Teachers can use the products to illustrate problems and concepts. These tools can also be used by students to assist them in solving problems.
Have fun and enjoy!