This Cyberchase activity addresses a common misconception that a phenomenon whose probability is 50:50 should alternate outcomes during trials. It gradually presents the law of large numbers by beginning with 4 trials, 10 trials, and 350 trials, and showing that the results get closer and closer to 50%. The activity is motivated by a Cyberchase For Real episode on making a decision about what movie to attend.
When Does 50-50 Become 50-50? QuickTime Video
Part I: Part I: Learning Activity
1. Distribute the Handout: Coin Flipping and More Flipping .
2. Tell the students that they will watch a video of Bianca doing an experiment.
3. As they watch the video clip, ask the students to make a record of each experiment Bianca does and to complete the first part of the handout.
4. Show the When Does 50-50 Become 50-50? QuickTime Video .
5. Ask the students to complete parts 2 and 3 of handout.
6. Discuss with students the results of the handout.
Part II: Part II: Assessment
Assessment: Level A (proficiency): Students are given the results of a survey of children's after-school activities, and are asked to predict from the survey how many of their classmates (out of 12) would be involved in a particular activity after school.
Assessment: Level B (above proficiency): Students are provided with results from 4 different experiments with different sample sizes, and are asked to determine which experiment's results are likely to be the most accurate.