Construction Chance Experiment: Mystery Bags brings probability to life through an engaging hands-on activity that encourages students to explore key mathematical concepts such as relative frequency, prediction, outcomes and sample size. By pulling different coloured objects out of a bag and tracking results over repeated trials, students develop a deeper understanding of how probability works in real-world contexts.

This resource promotes critical thinking and inquiry-based learning as students conduct trials, calculate outcomes and reflect on the accuracy of their predictions. With scaffolded worksheets and multiple trial lengths, students can clearly observe how increasing the number of trials impacts the reliability of results. Ideal for small groups, maths rotations or whole-class experimentation, this activity blends data collection with active exploration.

Key Learning Outcomes:

• ✅ Predict and test the likelihood of outcomes in a chance experiment
• ✅ Record and interpret data collected from repeated trials
• ✅ Calculate relative frequency and reflect on its connection to theoretical probability
• ✅ Understand the impact of sample size on the accuracy of predictions

What’s Included:

• Three activities for 10, 20 and 40 trial runs
• Tables for recording outcomes and calculating relative frequency
• Reflection prompts to guide mathematical thinking and discussion
• Experiment sheets to support individual, paired or group work

Materials Needed:

• Paper bag or similar non-transparent bag
• Three different coloured counters or similar objects
• Printed student worksheets
• Pencils or pens

How to Use:

• Introduce key vocabulary including prediction, outcome, relative frequency and sample size
• Guide students in making initial predictions about outcomes
• Have students conduct 10, 20 and 40 trial experiments using counters in a paper bag and record each result
• Support students in calculating relative frequency and comparing it to their predictions
• Use the reflection prompts to help students draw conclusions and discuss variability in outcomes

Ideas for Classroom Use:

• 💡 Set up multiple bags with varying amounts of each colour counter and assign different groups to each station to encourage comparison and collaboration
• 💡 Have students modify one variable, such as the number of a particular colour, and compare new outcomes
• 💡 Invite students to design their own chance experiment using classroom objects and present their findings to the class

Top Teacher Tips:

• 💛 Let students personalise their experience by choosing the objects to go into the bag
• 💛 Select the number of trials (10, 20 or 40) based on your students’ readiness and time available
• 💛 Send a simplified experiment sheet home to encourage families to explore chance and data collection together
• 💛 Alternate or use in conjunction with the other experiments in this series: Marble Run, Pendulum Hit, and Ramp Forks

Construction Chance Experiment: Mystery Bags is an exciting and practical way to support your students’ understanding of probability. With opportunities for prediction, experimentation, and reflection, this resource turns abstract concepts into concrete learning experiences that stick.