TL;DR: Check out Henrik Godmann’s “Probability Playground” with over 5 million simple exercises on probability theory!

Every year in September and October, Dora Matzke and I teach a course on Bayesian inference. Part of the course involves mastering Bayes’ theorem and the associated rules of probability — the law of total probability, conditional probability, the odds form and the probability form of Bayes’ theorem, etc. Although the rules are simple, our students are not used to applying such rules in a timed quiz, and over the years a recurrent complaint has been the following:

There are not enough exercises on probability theory in the syllabus. Can you please provide some? 

It did not really help that we pointed students to Google. This year we decided to put this question to rest once and for all with the “Probability Playground” (not to be confused with a very different Probability Playground, which focuses on probability distributions and looks pretty awesome!). This playground is the brainchild of Henrik Godmann, who designed it with the help of AI. The playground features 5,138,680 simple exercises on probability theory, spread out across a number of topics:

Once a topic is selected, the user is offered a problem to solve. For instance, selecting “Bayes’ rule” can bring up a question like this:

The app also provides guided steps, hints, and the answer. Check it out!

Eric-Jan Wagenmakers

Eric-Jan (EJ) Wagenmakers is professor at the Psychological Methods Group at the University of Amsterdam.