National Council of Teachers of Mathematics
The Math Forum: Intro to Fractions for Primary Students
This site from the Math Forum is a series of lesson plans with great ideas and an excellent Web site that uses virtual manipulatives with students.
National Council of Teachers of Mathematics
The Math Forum: Fractions: Middle School Lessons & Materials
A large archive of sites to help teachers with lesson plans and materials for teaching fractions. Geared toward middle school students and teachers.