Online middle school math lessons are available at MasterMath.info, MathPlanet.com and Khan Academy. All three sites have lessons on a variety of concepts and are freely accessible to students, parents and teachers.
MasterMath.info offers video math lessons for sixth, seventh and eighth grade math concepts, as well as Algebra I. Each lesson includes an online quiz and printable worksheets for additional practice.
At MathPlanet.com, middle school students can review pre-algebra, algebra and geometry concepts with illustrated examples and videos. Khan Academy sorts middle school math concepts by grade level and topic, based on Common Core State Standards. Video lessons and online practice problems are available for each skill.