This lesson is optional because it revisits below gradelevel content learned in grade 7 about chance events and probability. If the preunit diagnostic assessment indicates that your students know this material, this lesson may be safely skipped. The mathematical purpose of this lesson is to revisit the idea of chance events and the concept of probability. The probability of a chance event is a number between 0 and 1 that expresses the likelihood of the event occurring. The work of this lesson connects to previous work because students investigated chance processes and developed, used, and evaluated probability models in Grade 7. The work of this lesson connects to upcoming work because students will understand independence and conditional probability and use them to interpret data. The Which One Doesn’t Belong activity gives students a reason to use language precisely (MP6) and gives the opportunity to hear how they use terminology and talk about characteristics of the items in comparison to one another.
Lesson overview
 1.1 Warmup: Which One Doesn’t Belong: Spinners (5 minutes)
 1.2 Optional Activity: You’re Saying There’s a Chance? (10 minutes)

1.3 Optional Activity: A Fair Game (15 minutes)
 Includes "Are you Ready for More?" extension problem
 Lesson Synthesis
 1.4 Cooldown: What Affects Probability? (5 minutes)
Learning goals:
 Compare (orally and in writing) probability models and observed frequencies.
 Determine (in writing) whether a given situation involving probability is a chance experiment.
Learning goals (student facing):
 Let’s explore chance.
Learning targets (student facing):
 I can find or estimate probability using a model or data from a chance experiment.
 I can identify chance experiments.
Glossary:
 chance experiment A chance experiment is something you can do over and over again, and you don’t know what will happen each time.
 event An event is a set of one or more outcomes in a chance experiment. For example, if we roll a number cube, there are six possible outcomes.
 outcome An outcome of a chance experiment is one of the things that can happen when you do the experiment. For example, the possible outcomes of tossing a coin are heads and tails.
 probability The probability of a chance event is a number from 0 to 1 that expresses the likelihood of the event occurring, with 0 meaning it will never occur and 1 meaning it will always occur.
 sample space The sample space is the list of every possible outcome for a chance experiment.
 Access the complete Geometry Course Glossary.
Standards:
 This lesson builds on the standards: CCSS.7.SP.C.5MS.7.SP.5MO.7.DSP.C.5bCCSS.7.SP.C.6MS.7.SP.6MO.7.DSP.C.6aMO.7.DSP.C.6bMO.7.DSP.C.6cCCSS.7.SP.C.7MS.7.SP.7MO.7.DSP.C.7aMO.7.DSP.C.7bCCSS.7.SP.C.7.aMS.7.SP.7a
 This lesson builds towards the standard: CCSS.HSSCP.A.1MS.SCP.1MO.G.CP.A.1
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