I agree with mickmouse301-
FreeRice is an easy way to study vocab (and, it does help to know that you're donating to charity!)
Chances are if you spend maybe 20-30 minutes a day on it until the test, it'll help you on at LEAST 1 or 2 of the problems you see on the SSAT, probably more. If free rice makes any impact whatsoever on your score then I think that it is worth the time.