Elementary or Not?

Have you read the 512 Ants on Sullivan Street by Carol Losi? This is very short, rhyming story which I use to model exponential growth with my 7th graders.  Yes, I use this grade 2/3 with middle schoolers.

Reading this corny (or at least middle schoolers think it is) children's book is an easy way to introduce the powers of 2 when it comes to ants at a picnic.  We read the story aloud with no breaks and no prior discussion.  Then ask why I may be asking them to read such a story in math class.  The reply is typically "because it talks about doubling."  We then take turns reading sections of the text as a student to models the number of ants which join the parade at each stage of the story.  Our natural transition is to create a table, look for patterns, graph the data, discuss our findings and make predictions as to what would happen if this trend were to continue.

We take this introductory lesson to the next level by utilizing Excel to create tables, write functions and to graph the data.  Adding extensions as to what would happen if the ants tripled or quadrupled is common at this point.  How might the data change if only 2 ants joined it at each stage?  Can students predict at which point the ants will be over 1,000?

Taking this discussion to real life is the best part.  We talk about when exponential growth may be a positive and when it may be a negative....a great tie into science, cell growth, and bacteria spreading.

This next stage is to take the focus from a negative (i.e. the spread of illness) to a positive.  How can WE use exponential growth to to make a positive change in the world?  This leads into a great introduction to a Pay It Forward movement where each student is just one individual who can complete a good deed to 2 (or more individuals) asking for nothing in return but to simply pay it forward to 2 others....spreading kindness:)

Students brainstorm ways to spread kindness exponentially and put it into action.  We blog during to hear about challenges they encounter, ways to finalize their ideas and hear about the progress.  Their final task is to create a final project summarizing their kind deed, the mathematics behind it (a table, graph, pattern, function, etc.), photos, and a reflection.

The movie Pay It Forward makes a strong connection for students.  However, I have a clean-films version which has been edited (beyond PG-13) for school.  You may want to preview the content prior to showing this movie to your students.