3-Act : Dried Mango

Percent of change falls within the 7th grade standard domain of Ratios  & Proportional Reasoning. Knowing that students often struggle with this topic, I wanted to create a 3-act to aid in their understanding. I initially wanted to show the percent of decrease when making beef jerky. Due to aesthetics and cost, I dropped the beef jerky  idea and moved forward using the more cost effective mango.

Act 1Dried Mango – Act 1

Act 2:






Length of mango piecescreen-shot-2016-09-18-at-9-20-19-am







Width of mango piece




Screen Shot 2016-09-18 at 12.55.59 PM.png



Height of mango piece                            







Length of mango piece








Width of mango piece








Height of mango piece





Act 3: The Reveal

Once finished with the first 2 acts, I sat looking at my computer wondering about how to organize The Reveal.  Desmos to the rescue.  I created a Desmos double number line to track the percent of decrease.

0-0       12-5y


Multiple Representations


In anticipation of

  • student responses
  • exposing students to various strategies
  • and preparing to lead a whole class discussion by sequencing and  connecting differing strategies

my colleague, Mari, created the following summary.


Click here to see my other 3-act lessons.


About jgvadnais

Instructional Technology Coach. Desmos Fellow. Google Level 1 Certified. SoCal transplant. New Englander at heart. Lover of yoga, dogs, green smoothies and coffee creamer
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