"How much pizza...?" About adding fractions: Working with Improper fractions and Mixed fractions. The program build the problem, and you can solve filling the textboxes containing question marks. There's a tool that helps you find the common denominator.
Inspired by the works of Cynthia Lanius ("Who wants pizza?")
Nummolt - OBBL Math Toys
Math 3 Equivalent fractions
Math 4 Equivalent fractions, Simplifying fractions, Adding fractions, Fractions <--> decimals
Math 5, 6, 7 Equivalent fractions, Simplifying fractions, Adding fractions, Multiplying fractions, Writing decimals, Fractions <--> decimals
For more difficult exercises on fractions, we recommend:
Mathcats: "Old Egyptian Fractions":