Are those 2 groups different?

T-Test

May be a sticky header: reads it as "theory", "R code" or "Python code?"

give a good real life example

Explain that the data must be normal, otherwise it does not work.

Non normality: why does it break everything. What to do in this case?

Explain that there are 1 sample t test = to compare group to a mean and 2 sample t test = to compare 2 groups. Those will be the subgroups of this branch

I need a graph with 2 density charts.

Something I want to explain here is that if the sample size is very very high, then the p-value will most likely be significant. But the difference remains the same! It's important to keep in mind both the pvalue and the difference (t value?)

There should be an online calculator. You enter your data and it runs the test for you. Shows you the equation. With all the values in the equation.

R code and Python code of course.