Montana Math MT.CORE.DATA.PROB.2.a
The Standard
- MT.CORE.DATA.PROB.2
- Understand the concepts of conditional probability and independence in context. This standard should incorporate cultural context relating to Montana Indigenous Peoples and local communities by: Determining whether two events, A and B, are independent by using two-way tables, tree diagrams, and/or Venn diagrams, and interpreting the answer in context, and Computing the conditional probability of event A given event B by using two-way tables, tree diagrams, and/or Venn diagrams, and interpreting the answer in context.
Understand the concepts of conditional probability and independence in context. This standard should incorporate cultural context relating to Montana Indigenous Peoples and local communities by: Determining whether two events, A and B, are independent by using two-way tables, tree diagrams, and/or Venn diagrams, and interpreting the answer in context, and
2026 Montana Mathematics Content Standards · Data Reasoning and Probability
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students find the chance of a language session given that an event is on a weekend. They compare it with the chance across all events, then decide whether weekend dates and language sessions are independent.
What Mastery Looks Like
- A student can read a two-way table and calculate 8/20 for weekend events and 12/40 for all events. They explain that the features are not independent because 0.4 and 0.3 differ, and limit that claim to the events shown.
Common Misconceptions
- Students may divide by all 40 events when the question asks about weekend events only. Some confuse independence with events never overlapping, or treat a pattern in one calendar as proof of a cause.
How to Assess It
- Exit ticket: Of 40 fictional Montana tribal college events, 20 fall on weekends, 12 are language sessions, and 8 are both. Find the language-session rate for weekends and for all events, then decide whether the two features are independent.
Lesson moves
Ways to Teach It
Sort 40 fictional Montana tribal college event cards into a two-way table: 8 weekend language, 12 weekend other, 4 weekday language, 16 weekday other.
Ask, "If 8 of 20 weekend events are language sessions, but 12 of 40 events are, are weekend and language sessions independent? Why?"
Give pairs the 40 event cards; race to draw a Venn diagram and tree, then check whether both show the same conditional probability.
Print Salish Kootenai College and local library event listings; compare weekend rates by organizer, then limit your claim to the listed events.
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