Rumors – Exponential Growth

Overview: This lesson involves using a computer simulation to increase students’ understanding of the pattern and potential of exponential growth in a scenario involving the spread of rumors.  The computer simulation includes a scenario description, experiments with changes in variables, final conclusions, explanation of stock and flow diagrams, and related questions.  It is recommended that the teacher practice with the simulation first to acquire experience with the simulation and to facilitate decisions about the use of the explanatory text and questions following the simulation.  These decisions will greatly depend on the reading level of the students.

Lesson Objectives

Lesson Context


  • To increase students’ understanding of exponential growth.

  • To increase students’ understanding of spreading rumors as an illustration of exponential growth

  • To increase students’ awareness of the difficulty in stopping rumors if there is a delay between the start of the rumor and the attempts to stop it.  

Optional:  To develop students’ understanding of the concept of stock and flow diagrams

This lesson can be used in a variety of contexts.  Examples include: math or science classes to illustrate and develop understanding of exponential growth, language arts classes as an introductory activity before reading related text or as a prompt to stimulate ideas for a writing assignment, and social studies classes to illustrate and develop understanding of the spread of ideas, propaganda, etc.

  • generic structure

  • reinforcing feedback

  • exponential growth



Systems Tools

  • STELLA® Software available from isee systems – (see the Read Me First file in the lesson materials)

  • Rumors computer simulation which is available with the download of the complete lesson plan.

  • One computer and projector for large group presentation or multiple computers for small group or individual work.

  • 2-3 hours plus possible extensions to related curriculum and/or concepts

  • Stock/flow diagrams

  • Computer simulation

  • BOTG

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