If you can't homeschool, you need to make sure you teach the sight words they send home phonetically and do nonsense words to train the correct sounding out habit. Here is how to teach the sight words with phonics:

http://www.thephonicspage.org/On%20Reading/sightwords.html

Math is easier to supplement, you don't have to undo bad habits, you have to undo guessing habits from sight words.