Descriptive statistics including correlation and curve fitting. Design of experiments. Intuitive treatment of probability and inferential statistics including estimations and hypothesis testing.
I think that the primary importance for further statistical treatment is correct design of the experiment. For example, you can consider only population which respond to one or another stimuli with the same way, but you can not mix several population what have opposite response to the same stimuli. As an example we can consider investigation of gene expression in muluticellular organism which consist form different cell types. In reality these cells may react differently, even opposite to changes in environment. So, in this case "average in gene expression" do not have any meaning.
Descriptive statistics including correlation and curve fitting. Design of experiments. Intuitive treatment of probability and inferential statistics including estimations and hypothesis testing.