Crescent Dunes

3 Act Math, Daily Overview

Crescent Dunes


Michael Fenton and I are teaming up to create a bunch of math tasks inspired by Daily Overview images, and we created a new site to house the tasks. Also, we’ll be tweeting the tasks using the hashtag #DailyOverviewMath.

Act 1:

How many heliostat mirrors will be there when the construction is finished?

Note: Jedidiah Butler mentioned that this is similar to Dan Meyer’s Burning Man task. Check it out!

Act 2:

What information would be useful to figure this out?

The inner and outer diameter of the circle is necessary for a good calculation. As usual, I would prefer to let the students retrieve this information on their own using a Google Maps Engine. Here’s a tutorial video if you’re not familiar with the tool. If that’s not an option for your classroom, we provided pictures.


The students also need to know how much space each mirror occupies.

Mirror Dimensions
They may also want to determine the spacing between the mirrors using estimation or the maps engine.

Act 3:


How much will the project cost?

Official Lesson Page:


  • Common Core
    • 7.G.6 – Solve real-life and mathematical problems involving angle measure, area, surface area, and volume.
    • HSG.C.A – Understand and apply theorems about circles
    • 7.RPA – Analyze proportional relationships and use them to solve real-world and mathematical problems.
  • TEKS
    • 7.9B – Determine the circumference and area of circles
    • 7.9C – Determine the area of composite figures containing combinations of rectangles, squares, parallelograms, trapezoids, triangles, semicircles, and quarter circles

Daily Overview / Satellite imagery courtesy of Digital Globe / Benjamin Grant

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