FREE Jo Boaler Course: How to Learn Math is a free class for learners of all levels of mathematics. There are 6 sessions, the first three are approximately 10 minutes long and the last three approximately 20 mins long. It combines really important information on the brain and learning with new evidence on the best ways to approach and learn math effectively.
Kutasoftware.com: More practice by topic. Answer sheets are provided.
WorksheetWorks.com: At this site you can customize the worksheets by topic. Answer sheets are provided.
MathWorksheeets4Kids.com: This is also a site you can customize by topic and answer sheets are provided.
IXL.com Sixth Grade Math: In the free version there are a limited number of problems you can do before you are locked out. There are both monthly and yearly pay options available.
Math-drills.com : Even more practice worksheets with answers. The worksheets are good but the website has a lot of pop ups and you need to indicate that you don't want cookies every time you switch pages.
Khan Academy : You can learn anything. Use for re-do and acceleration.
FrontRow: Practice math fluency (2x per day). Supplemental lessons by standard.
Xtramath: Help kids master basic math facts.
Desmos: Easily graph functions, plot data, and explore transformations with this easy to use web application
Mathx.net: More practice sheets with answers, but you have to navigate around a little more and avoid ads.
College Preparatory Mathematics (CPM) Resources
Sometimes students and parents want an alternative explanation of an idea along with additional practice problems. The Parent Guide resources are arranged by chapter and strand. The format of these resources is a brief restatement of the idea, some typical examples, practice problems, and the answers to those problems. The format resembles a traditional math textbook.