Measures of Variation & Dispersion
Range
Basically just the difference between the largest and smallest value in the data set, range in statistics class is the same as it was in middle school.
Estimating Standard Deviation via Range Rule of Thumb
This is a very specific method that not all stats classes cover. But if yours does, this video lays out the concept and shows you how to work the problems forwards and backwards.
Standard Deviation of Samples vs Population
This video covers how to find standard deviation for population and samples, and it also gets into the differences between the formulas. Why is there an n-1 in the denominator of one formula but N in the other?
Standard Deviation On Your Calculator
Calculators are awesome for stats. This video shows you how to get those key stats -- including standard deviation for samples and populations -- as quickly as possible, and also making sure you grab the right one!
Bias of Standard Deviation vs Variance
No matter if you're in the easiest Statistics class ever, or the hardest, your professor probably expects you to know that sample standard deviation is a "biased" estimator, whereas sample variance is an "unbiased" estimator which "targets" population variance. But what the heck does that mean? Yeah, stick around.
Coefficient of Variation
Coefficients of variation are at least mentioned in most stats books, but it's a coin toss as to whether your professor expects you to know them. If it showed up in your homework or notes, this video is for you, though it's not exactly the hardest concept you're going to see in this class.