Getting started with middle school math
If your student has been in public school, you may not know where they are in math. There are online placement tests, which can be useful but aren't really necessary. If you use the first few months of homeschooling to slowly work with your child, you'll get to know what they know. Look at a practice book together (such as the Evan-Moore or Spectrum series at bookstores). Have your child try various problems. That will help you find any gaps in their skills and know where to start.
In most schools or curriculums, approximately the same math topics are covered in 6th, 7th and 8th grade, but with increasing level of complexity. Some kids are ready for Algebra 1 in 8th grade, with others need another year of firming up the basics of Pre-Algebra.
Order of operations (PEMDAS)
Operations with negative numbers
Equivalent fractions and decimals
Variables and algebraic expressions
Operations with fractions and decimals
Ratios, Rates and Proportions
Percentages
Basics of geometry, surface area, volume
Graphing linear equations
Solving one- and two-step equations and inequalities
By this level, most parents find it helpful to have a math curriculum or online lessons of some sort. You may find your head spinning. Just take a deep breath, read reviews, make your best guess and try one. Don't spend too much money right away. If one doesn't work, talk to other parents and try again with something else.
"Circular" or "Spiral" means lots of review is worked in, for those who tend to forget previous techniques
"Mastery Based" means it moves along to the next topic without too much review.
When choosing, also consider how much teaching you want to do, versus independent learning. Some math curriculums are self-taught, other assume a parent is teaching the lesson first. Does your child learn math best by reading, watching a video, or talking it out?
There are so many options, instead of listing a few here, please see the complete Math Curriculum page.