Teachers I have ??

I am going to start studying for the GMAT on my own before I take a class. I took a practice test and I did HORRIBLE!!! So embarrassed to even say what I got. Anyway, many of the basic grammar and math skills I learned back in what 8th grade?? I completely forgot. How I did well in college 5 yrs ago and forgot everything now is beyond me. I feel like a dope!

Do you use any type of materials to help your students in these areas? I know Scholastic does workbooks on algebra and trig so just wondering if you use anything that you feel is better and easier to understand. Also any vocabulary websites or books would help.
Thank you.