What's in the modules?
S1
Mathematical Models Measures of Location Measures of Dispersion Representation of Data Probability Correlation Regression Discrete Random Variables Normal Distribution 
S2
Continuous Distributions Continuous Random Variables Discrete Distributions Discrete Random Variables Hypothesis Testing Modelling Probability Sampling Methods 
S3
Combining Random Variables Sampling Estimation, Confidence Intervals and Tests Goodness of Fit and Contingency Tables Regression and Correlation 
Revision Materials
Page Summaries
S1 S2 A useful and succinct set of S1 Revision Notes. Revision Resources Normal Distribution Questions and Answers 
Amusing harder questions on conditional probability and Venn diagrams. And some answers when you have had a go.
An excellent website with lots of permutations and combinations questions. Multiple choice and answer online, but the working out will need to happen with pen on paper!

Reading Material
On the pros and cons of the standard deviation compared to other methods of measuring the spread of a set of data.
CORRELATION DOES NOT IMPLY CAUSATION
So this website is funny rather than meaningful.
