This video introduces a few aspects of the Chi-Square distribution that you're supposed to know off the top of your head, either for the test or because it will help you get what's going on with the problems that use this funky distribution.
Chi-Square Critical Values
Like all the other distributions you use in stats, with Chi-Square you frequently have to turn to a table and look up the "critical values" for the problem you're working on, which basically means finding the value of Chi-Square which creates a "tail" with an area of .005 or .05 or whatever level of confidence you're working with.
If you do not have an account, you should get one, because it is awesome! You can save a playlist for each test or each chapter, and save your "greatest hits" into a "watch right before the final" list (not that we recommend cramming, but when in Rome...)