It is almost impossible to study
psychology without a good knowledge of research methods, or methodology, and
some knowledge of statistics.
Here is a basic
package on research methods which will supplement your class sessions.
It’s well worth working through.
Check out these links: all about
variables, correlation and experiments in
language that is probably less technical than your text books. It
includes basic stuff about experiments and some more advanced stuff about
statistical testing and probability.
Powerpoint which might help your understanding of
levels of measurement
Notes on
reliability and
validity
Here is an amazing American
online stats book, which
may have more than you actually need but really is useful in learning stats.
Teachers might find this particularly helpful.