Lesson objective: Practice using addition to find the probabilities of "at least," "or," and "less than" *with replacement.*

This lesson helps to build fluency with using multiplication to find the probabilities of independent compound events and addition to find the probability of one compound event or another. An equation is used here because it highlights using multiplication to find the probability of each independent compound event and addition to find the probability of one compound event or another. This work develops students' understanding that probabilities of independent events have the same number of possible outcomes for each event and that the outcome of one event has no effect on the outcome of another event.

Students engage in Mathematical Practice 5 (using appropriate tools strategically) as they use equations to find the probability of independent compound events.

**Key vocabulary:**

- at least
- independent events
- less than

**Special materials needed:**