Reflection: Connection to Prior Knowledge The Cost of Debt (Part 3 of the Spending & Saving Project) - Section 3: Work Time and Extensions

A student stuck around after school today to work on her project, and without prompting, she realized that she could use the spreadsheet introduced in today's lesson to help finish her work on Part 2 of the project.  This was the first time I've seen a student do that, and I'm so impressed!  I'm most impressed because this was her own idea, and this move indicated her understanding of how different parts of the project fit together.  Check it out: U4 L15 Using Spreadsheet.jpg

Also exciting was that she realized that the "# of months column" on the spreadsheet was, in her words, "one off" from the actual x-values used in Parts 1 and 2 of the project.  This opened up the conversation we had about what different inputs mean in different function situations.  We also recognized that a positive value in the "Monthly Payment" field was successively subtracted from the "Remaining Debt" values in that spreadsheet column.  So when it came time to use the same trick to help her look at an increasing linear function, she could type a negative value into the Monthly Payment field, which, doubly-negated, would yield a positive change on the spreadsheet.

It's so exciting when students make these tools their own, and when doing so opens up new ways to think about functions.  In the future, I'm not sure if it will ever be worth it to reveal such a trick to students, but I'll certainly be happy to have it my back pocket, and might find it a useful exploration for an after-school work session.

Connection to Prior Knowledge: This is Cool! Using the Spreadsheet to Complete Part 2

The Cost of Debt (Part 3 of the Spending & Saving Project)

Unit 8: Linear and Exponential Functions
Lesson 15 of 19

Big Idea: Debt is not free, but students can make sense of how to make it more or less expensive.

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43 minutes

James Dunseith

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