Online calculators and articles
Here is a set of online articles that help understand the mathematics behind Agile. We add to these all the time and would like to hear ideas you have for more.
Forecasting and Metric Spreadsheets
To be honest, you probably know us because of our spreadsheet tools. That's OK, but now consider training :)
KanbanSim and ScrumSim Application - just download and unzip, requires Windows (just get a free VM on Amazon or Azure and simulate there)