This IB Maths AA SL Topic 4.6 – Rules of Probability resource develops students’ confidence in representing and calculating probabilities using Venn diagrams, sample space diagrams, tree diagrams, and tables of outcomes. It begins by introducing the language and notation of sets, including intersections, unions, complements, subsets, and mutually exclusive events. Students learn how these ideas represent “A and B,” “A or B,” and “not A” within a probability context.

The lesson then develops students’ understanding of conditional probability through expressions such as P(A given B), before applying these ideas to survey and diagnostic-testing problems. Students practise organising information in Venn diagrams, calculating probabilities from overlapping sets, and interpreting branches in tree diagrams. The resource also uses tables of outcomes to list joint events, calculate probabilities such as “at least one,” and verify independence using P(A and B) = P(A) × P(B). With clear diagrams, worked examples, contextual problems, probability notation, modelling strategies, and fully worked solutions, this resource helps SL students build strong probability reasoning in line with IB Mathematics AA expectations.