What are some good ways to teach the content that you are required while also remediating concepts that should have been learned many years earlier? I teach high school algebra but find that many students can't successfully add, subtract, multiply or divide nevermind deal with fractions, decimals, and percents.
For +, -, x and /, I have a very concrete suggestion: KenKen puzzles! Check 'em out at www.kenken.com. One easy way to do this is to give kids a puzzle on Monday and require that it be completed and submitted by Friday (possibly for extra credit??). I've found that even kids who don't really like math get into KenKen -- it's a puzzle, so they're a little more motivated, especially when they start having a little success.
My friend Rhonda tackles remediation with technology. She has lots of skill-based software on the computers in her classroom, and when students have "free time" to do homework, etc., students who need remediation can go to the computers to practice. Of course, students wouldn't just choose to do this -- so for those students who need it, she sets up a system where completing certain sections in some of the software is a requirement. I remember that she hated that 8th grade students would come to her so deficient with fractions, so she'd often require many of them to complete the first several levels of a fraction program during the first grading period, and their class grade was dependent on its completion (it wouldn't be graded like other stuff, it was just P/F... but if certain levels weren't completed by the end of the first grading period, the student would receive an "I" (incomplete) for their math grade). Students could also come down during their free time throughout the day (study hall, lunch) and work on the software then, too.
Personally, I think it's all about embedded review. When working on a new concept or skill, I'd be sure to review the requisite skills.
There is a really cool game show here in Australia called Letters and Numbers. I think it would be great to recreate this game in your classroom. Your students would have fun while practicing adding, subtracting, multiplying and dividing. Go to the hyperlink above and watch an episode. Since you teach math, you could just do the "numbers" portion. So basically, you select 3 random small numbers and 3 random larger numbers and you select a target numbers the students have to reach using any or all of the 6 numbers. Students can add, subtract, multiply or divide any of the numbers in any order to get as close to the target number as they can. The great thing is that they don't have to come up with the exact answer and they will come up with so many different ways to get to their answer.
I play it with my whole family and even my 2nd grader has fun solving the math problems. My fifth grader and husband are are good at figuring out the answers in their heads, while I have to use a paper and pencil for my math calculations;) If you just want them to compete with themselves, you don't need to select "winners", just have them keep the answers to themselves and challenge themselves.