Chime Lab: Which Peg Gets Hit Most?
If eight pegs were hit equally often, each would get one eighth of the hits: 12.5 percent. Students guess, then let three balls bounce for a minute while the app counts. The bottom peg gets about three quarters of all the hits and the top five almost none. They roll new luck and run again, plot the class's results, and find the share barely moves: a long-run relative frequency they can use as a probability. Then they hunt for the one setting that makes the pegs close to fair, and explain why gravity, kick and bounciness cannot do it but a turning ring can.
At a glance
Essential question
How can data tell you whether a chance process is fair?
Objectives
Students will be able to:
- find a relative frequency as a fraction, decimal and percent of all trials
- compare observed frequencies with an equally likely model and decide whether the model fits
- build a probability model from data, and use it to predict
- change one variable at a time and use data to explain its effect
Vocabulary
trial, relative frequency, probability, equally likely, probability model, variable
Standards
7.SP.C.5, 7.SP.C.6, 7.SP.C.7.b, 6.SP.A.2, 7.SP.C.7a
Time and materials
45 minutes, grades 6-8.
- One computer or Chromebook per student or pair, with headphones
- A projector
- The worksheet and exit ticket, one copy each per student
- A number line on the board from 50 to 100 for the class dot plot
- The rubric, one copy per student if you grade the worksheet
Prep
Make copies of the worksheet and exit ticket, and draw a number line from 50 to 100 on the board. Before class, open mytekdev.com/try/chimelab?lesson=which-peg-gets-hit-most&ref=tpt-chimelab-2 once on a student computer to see the ring and to check that your school's filter allows it. No account is needed. Lesson 1 (Same Bounces, Different Mood) is helpful but not required.
Assessment
- Formative: the questions under What to look for, asked while students work, and the exit ticket (answer key included).
- Summative: the completed worksheet, including the data table, the model and the experiment, scored with the rubric out of 12.
Technology and privacy
Runs in any browser, Chromebooks included, with nothing to install. Students need no account and no email: the link works signed out, and nothing they make is stored on our server unless they choose to save it to an account. The ring plays notes, so headphones help. If your school blocks new sites, ask IT to allow mytekdev.com.
What’s included
- A one-page overview: objectives, essential question, vocabulary, standards and assessment
- A 45-minute lesson sequence: warm-up, direct instruction, guided practice, independent practice, closure
- Slides for the board: a PowerPoint file that also opens in Google Slides
- A student worksheet with a QR code
- A 3-question exit ticket, two to a page, with an answer key
- A rubric: 3 criteria, 4 levels, scored out of 12
- Differentiation for English learners, students with IEPs or 504 plans, and students who need more support or more challenge
- Cross-curricular extensions, and notes for teaching it in grades 4-5 and 9-12
- Standards: Common Core math
Standards
Probability from data is the center of this lesson.
| Framework | Code | Grades | Standard | How the lesson meets it |
|---|---|---|---|---|
| Common Core Math | 7.SP.C.5 | 7 | Understand that the probability of a chance event is a number between 0 and 1 that expresses the likelihood of the event occurring. Larger numbers indicate greater likelihood. A probability near 0 indicates an unlikely event, a probability around 1/2 indicates an event that is neither unlikely nor likely, and a probability near 1 indicates a likely event. | Students give each peg's chance as a number from 0 to 1: about 0.75 for the bottom peg. |
| Common Core Math | 7.SP.C.6 | 7 | Approximate the probability of a chance event by collecting data on the chance process that produces it and observing its long-run relative frequency, and predict the approximate relative frequency given the probability. For example, when rolling a number cube 600 times, predict that a 3 or 6 would be rolled roughly 200 times, but probably not exactly 200 times. | Students collect a minute of hits, repeat with new luck, and predict W1's hits in 300 more. |
| Common Core Math | 7.SP.C.7.b | 7 | Develop a probability model (which may not be uniform) by observing frequencies in data generated from a chance process. For example, find the approximate probability that a spinning penny will land heads up or that a tossed paper cup will land open-end down. Do the outcomes for the spinning penny appear to be equally likely based on the observed frequencies? | Students test an equally likely model against the data and build a non-uniform one. |
| Common Core Math | 6.SP.A.2 | 6 | Understand that a set of data collected to answer a statistical question has a distribution which can be described by its center, spread, and overall shape. | The class plots W1's percent from every roll and describes its center and spread. |
| Common Core Math | 7.SP.C.7a | 7 | Develop a uniform probability model by assigning equal probability to all outcomes, and use the model to determine probabilities of events. | Students assign each of the eight pegs the same chance, 1/8 or 12.5 percent, and use that model to say what a fair minute of hits would look like. |
Checked October 2026 against: Common Core State Standards, Grade 7 Statistics and Probability, Common Core State Standards, Grade 6 Statistics and Probability.